The Herd Mentality v. Self-Control

My grandparents were born in around 1900. The emigrated to the US in their 20s and soon after had accumulated enough money to buy a car. They liked to drive. However they were not so great with directions. When my grandfather didn't know in what direction to go, my grandmother would helpfully advise, "Follow him. He looks like he knows where he's going."
Have you heard of the phrase, 'herd mentality'? Wikipedia explains it,

Herd mentality, or mob mentality, describes how people are influenced by their peers to adopt certain behaviors.

Or this from The Royal Society,

Herding can be defined as the phenomenon of individuals deciding to follow others and imitating group behaviours rather than deciding independently and atomistically on the basis of their own, private information. Article- Herding, social influence and economic decision-making

We see the follow-the-crowd mentality in stock markets and even in home design trends.
Sociologists researched this phenomenon at Leeds University.

Researchers at Leeds University performed a group experiments where volunteers were told to randomly walk around a large hall without talking to each other. A select few were then given more detailed instructions on where to walk. The scientists discovered that people end up blindly following one or two instructed people who appear to know where they’re going. The results of this experiments showed that it only takes 5% of confident looking and instructed people to influence the direction of the 95% of people in the crowd and the 200 volunteers did this without even realizing it. (Source)

Herd mentality is real. Following a crowd in home decor trends is not a dangerous activity, but other follow-the-crowd activities are.
Parents often worry about their teenager falling in with the wrong crowd. That's because they know how impressionable youths can be and how easily they can be led to certain behavior through peer pressure. It's one reason I object so strongly to the exclusion of parents or other adults from the youth-oriented Passion conferences. This is a conference where tens of thousands of youths congregate for allegedly spiritual purposes, to receive instruction, and to engage in social justice activities. This last is helped along by the organizers having stationed many ATMs throughout the venue so the youths will donate money to social justice causes. And they do. Of course, donating to charities is not bad, but arming teenagers with credit cards, separating them from their parents, and inoculating them with incessant sermons preaching about donating to social causes, means it's easy to induce the desired behavior from your captive subjects.
However, the herd mentality phenomenon is not restricted to youths, as the example above from Leeds University shows. Here is an example from the Bible which shows, in my opinion, just how easily led the heart and mind can be. In this example, we see how easily adults can fall prey to blindly following a crowd.
So the city was filled with the confusion, and they rushed together into the theater, dragging with them Gaius and Aristarchus, Macedonians who were Paul’s companions in travel. 30But when Paul wished to go in among the crowd, the disciples would not let him. 31And even some of the Asiarchs, who were friends of his, sent to him and were urging him not to venture into the theater. 32Now some cried out one thing, some another, for the assembly was in confusion, and most of them did not know why they had come together.  (Acts 19:29-32).
The scene is Ephesus, and Paul is preaching. Ephesus was a wealthy city with numerous guilds such as coppersmiths and silversmiths. The smiths were engaged in a monetarily healthy trade in making false idols to the local deity, Artemis. Demetrius, a silversmith, had quickly seen the effect Paul's preaching had had on the city's new converts. They no longer bought idols of silver, and his income was affected. This could not stand. Demetrius incited a riot. The city-folk streamed into the amphitheater.
One reason I love the scriptures the way they are written is the Holy Spirit-inspired details. If you read the entire passage in context, It's pretty dramatic. The scene is vivid. Picture any B-movie from the 1950s where the villagers are storming the castle with pitchforks. The crowd is unruly, loud, angry, and dangerous. They were also intent on making their point and the adrenaline rush of fury and tumult carried them along. But then you see the few words at the tail end of verse 32, lol.
most of them did not know why they had come together
MOST of them
did NOT know why
they were THERE
Not a few of them, not that some of them, MOST of the people did NOT know why they were headed up the hill and sitting at the local colosseum yelling their heads off.
I'm reminded of this past week's Women March on Washington where thousands of feminists streamed to the capitol to demand nebulous 'rights'. However, when Christian reporters and theologians who were there interviewed several women and asked them why they came, the women didn't know. It reminded me of the riot in Ephesus all over again.
If you read to verse 34, it says But when they recognized that he was a Jew, for about two hours they all cried out with one voice, "Great is Artemis of the Ephesians!"
I'm sure you've ever been to a high school pep rally or a sports event. The crowd stomps the bleachers and sings 'We will rock you', we are the champions' etc. We have Queen to thank for his everlasting rally cry. Listen, if you will, to the first 35 seconds or so.

I avoid loud gatherings as an adult, but in high school pep rally assemblies were compulsory. I vividly remember the reverberations of the bleachers, the stomping, how quickly the first stomp grew to a unified sound that morphed into the song. It went on for a while, maybe a few minutes. But it didn't last long. It's hard for a crowd to remain vigorous in its unified efforts and soon the effort fall apart into distinct voices and scattered stomps, then ended.
In Ephesus, they cried out with one voice for two hours. Just imagine if the entire football stadium was singing 'We will rock you' for two hours, solid.
We see another mob mentality moment in Genesis 19:4-11. The scene is Sodom and the place is Lot's house. The mob surrounded the house where the two angels dwelt and pressed so hard against the door that the angels struck them blind, but they still groped for the door.
Imagine the scene just prior to this, though. The news that two handsome men - strangers - were at Lot's house spread through the city like wildfire. The verse says that men from all quarters of the city came to Lot's house. The news spread and it ignited feet. Soon the men were like pillaging villagers ready to storm the castle, or in this case, Lot's door. An entire population rushed there, yelling, demanding, just as the people did in Ephesus.
I think these examples of herd mentality (and also the example of the angry mob that stoned Stephen in Acts 7) show just how sinful we are. Even after salvation, the tendency to follow the crowd is still present in the heart and mind, because we are still sinners and not glorified yet. I believe this is why so many passages and verses advise wisdom and self-control. I think it's especially important when a church is considering leaders for their local body. Anyone who consistently engages in self-controlled, measured actions based on wisdom and not an unreasoning follow-the-crowd mentality is definitely leader material.
But the fruit of the Spirit is love, joy, peace, patience, kindness, goodness, faithfulness, gentleness, and self-control. (Galatians 5:22-23).
Strong's Concordance says of the word self-control here-

egkráteia (1466)  – properly, dominion within, i.e. "self-control" – proceeding out from within oneself, but not by oneself.
For the believer, 1466 /egkráteia ("self-control, Spirit-control") can only be accomplished by the power of the Lord. Accordingly, 1466 /egkráteia ("true mastery from within") is explicitly called a fruit of the Holy Spirit (Gal 5:23).

Paul talked about this exact kind of self-control to Felix in Acts 24:25. Peter talked about self-control in 2 Peter 1:5-6,
For this very reason, make every effort to add to your faith virtue; and to virtue, knowledge; and to knowledge, self-control; and to self-control, perseverance; and to perseverance, godliness; 
It's easy to follow a crowd. All too easy. It's hard to withstand the stream of thousands of people headed in one direction. It takes self-control to stop either actually or metaphorically as you're buffeted by people all around you headed in a certain direction and you're not at all sure you want to go. It takes strength to stand quietly for a moment and think, assess, and pray for wisdom. It is very hard NOT to follow the crowd.
But always remember that self-control is a fruit of the Spirit. Though we have the sinful tendency in us to easily become unreasoning animals and follow whatever crowd is doing, we have the Holy Spirit. Self-control proceeds out from within us, but is not by us. It's Him. All him. When we rely on the Spirit to induce in us the control we need, Jesus receives glory.