TLDR, Social media, Algorithm, technology (smart phone with access to high speed internet and unlimited data plans) allows people to pipe into a neverending feed of content designed to high jack your shyt. This is just the first wave of people who been tapped in last few years.
Long answer, I lived that 2013-'15 wave as an experienced vet armed with years of experience and getting exposed to online spaces like that (though I would say it hurt in beginning than actually helped). Only era better than that was when we were using promoter type software on myspace and essentially turned the website into a dating site where we were the only guys. Myspace let you search by area, build (slim athletic, thick or whatever but incredible, lol) age group, ethnicity, etc. Imagine I could say I want all the 21-25 AA athletic girls in miami and mass text hey you look familiar or cute and get 50%+ response rate. It was that ridiculous, that program did have them introduce captcha tho but we were eating off that for yearssss. Because it was new and unfamiliar. Same like when I was sending direct mail for homes back in day, response rate was incredible, when competition increased, response rate dropped.
I would think many are familiar with the paradox of choice, when exposed to multiple options humans tend to be unable to make a choice. That is what we are seeing now, the type of abundance that makes people unable to choose at all. Add on that time frame you mention, IG hit tipping point around same time, going from like 50 mil to like 500 mil monthly users from the run up of 2013-'15. In that time it went from iphone only to Android, added videos, direct messages, ability to go live, etc. But biggest glitch is when they do their full redesign and go from chronological to algorithm based post first. If there is an algorithm then it can be manipulated and certain people will be pushed and then masses can be influenced. Around the same time, cameras on phones go from ehh to actually decent enough, unlimited data plans were introduced around same time, I think Tmobile was leading the charge in that 2014-16 era.
I lay down all of that to say even with us getting a glimpse of how bad it was with reality tv and women actually watching basketball wives and bad girls club type stuff, it was mainly tied to tv. When IG allowed people to build up followings and then communicate directly then you had even the person on meds being able to have ability to influence the masses. My city is the fronting capital of world, it was IG before IG. People fly here, rent a lambo and be whoever they want to be for weekend, IG allows people to build entire personas online and have people follow into perpetuity. People are literally connected to social media like an IV. I was talking to a 24 year old girl met recently and on first night out I swear I was talking directly to an algorithm. EVERY social media buzzword in first convo (Demure, toxic, narcissist, self care/love, boundaries, gaslighting, etc.) Maybe its the marketing/ad background that has me like but I know when I hear it and I just start going thru the motions. Show me your IG, do you watch youtube? Lemme see, is this your only account? What dances you do on tiktok (the greatest algorithm ever created since i havent mention yet and since they started as kids app, they hijacked gen Z or is it Gen A?) You get someone access to phone and you have everything you need to see whats really good. This is better than when the old school playas used to read their girls diaries (yes I had older cuz who did that when I was jit) Hopefully this mess makes some type of sense, I should of ran it thru AI to clean up..
The points you made about reality TV too, that I didn't hit. 100%. My sister told me about that, since I never watched it, and don't have social media.
but people could see reality TV which is already very very influential on behavior, and then mimic it on social media, and in their daily lives.
The way people hold their phones even comes from The Kardashians, hand outstretched, phone out, turned to the side. Once you notice it, you will see it everywhere. Peoples small time drama became social media wars in their own circles. They learned how to sub people, passively aggressivly like people's stories, signal their in group or out group affiliation, to socially sanction people via public shamings, and unfollowing, group chat politics. The drama is always there, one text away, one like away.
and then like you were sayin marketing.....the thing with social media is that it's subtly always selling you the idea that you can be famous influencer too. Even if that makes up a 0.02 percent of all users, who even make 50K a year, it is something that everyone is competing for. Likes and follows.