Other people are not doing any better than you. It is an illusion. Many are full of debt trying to pay for a lifestyle way over their heads.
Some of them are in over their heads, yes. And it will catch up to them sooner rather than later, once their age starts to show and the income slows down they will discover that being an instagram model/star doesn't translate well to actual careers. Others are making bank, being smart with their money (renting a car/house for a shoot rather than buying, borrowing the same things, going in as groups to even the cost) and investing for the future. It all depends on their mindset, and how they manage their money. However, I fear the smart ones are in the minority so a lot of them will wind up marrying into money to keep the lifestyle going or going the crash/burn route where they suddenly find themselves saddled with bills they can't afford and long standing debts they can't pay. The same goes with youtube/twitch stars, a lot of them will end up in the same boat where eventually they will have to either branch out or die the death of a thousand unsubscribes.
The real problem I have with all of them is that they don't tell the people following them that yes, they put in a lot of work to do what they do and it costs them a lot of money to keep it up. They act like it's all fun and games, and that everyone that does it is just living the best lifestyle possible with no worries. It gives people a very unhealthy mindset about the entire thing and leads people that look to them as something to aspire to an unhealthy mindset, teenagers and young kids especially which in turns leads to things like depression.
Now mind you, not all social media types are bad. I follow one gal who does modeling, makeup shit, and shows all the concerts and whatnot she goes to. But she also talks about the work she puts in, having to learn new tax codes, and most importantly the stress it puts her under some days as she has had to deal with stalkers, people stealing her content and online identity, and less than savory types that have tried to exploit her into doing porn (she is 100% against ever doing it) or other less-than-legal acts. But sadly I doubt she will ever really take off because she isn't all glamour and fun and talks about the dirty side of doing it all when most people don't want to hear about that. Which is a real shame, because she is very real and upfront about it all and paints a MUCH more realistic picture of what its like to be an online model.
There are also lots of social media people that aren't just about making money. Some talk about their hobbies and actively participate in them on their shows (video games are big for this now), others try to teach useful skills to people that never learned them, while some are just people who are having fun doing random shit. These people are, for the most part, great to watch because you know they are not only enjoying that they do but they are happy to educate others and have fun with their fans.
All in all, social media can be a great boon to society as you can reach other and find others that enjoy your hobbies, teach you things you wouldn't be able to learn otherwise, or sometimes just help you escape from reality for a while and relax. But at the same time, it's a poisonous well that can quickly bring you down and do it's best to ruin you if you aren't careful. It's all about how you use it, and how you let it affect you. Some people handle it well, others don't. Personally I pick and choose who I follow online very carefully as I don't want to get into the habit of trying to follow the online joneses. I've gotten rid of facebook and twitter entirely (because fuck them) but still use youtube and some limited instagram mostly for hunting/fishing types and a few wookworkers whose skill I admire, plus a couple comedy shows and the one model I previously mentioned (whom I actually first met in real life entirely by accident).
Is social media poisoning our brains? Yes, it is. But only because we let it. Should something be done about this? Yes, people are using it to get an unrealistic picture of what they think the good life is, finding echo chambers so they never have their beliefs questioned, and attacking others though it so it's obviously a problem. The question is WHAT we can do about it. We can't ban it, the genie is out of the bottle. Regulating it is almost impossible at this point. The most we can do is watch out for others who are delving into the problematic uses of it all, and try to stear them clear of it and help them when that fails. And if we can't, well... sometimes you have to sit back and watch the building burn.