Have you considered "it" can both be a problem that is personal and also systemic? I'll take just one issue you posted.
If 70% of Americans are overweight or obese, it's not just a personal problem. How come it wasn't a "personal problem" just 40 years ago? Are you aware that our food supply is basically poisoned with high fructose corn syrup?
If you want talk about "brains" you should be able to pull out from your small minded thinking and look at the problem from a macro perspective.
40 years ago, were we calling overweight an eating disorder? Whether covid or gen Z awareness; the fact is, buffets are on the decline. Things self correct. Although we may have corrected the eat all you want world view into take selfies at a 9/11 memorial because someone who is bmi healthy is still totally fucked up in the brain stem for internet click baits.
You & I care about the future. But I will tell someone to their face to, "Do better.", while you may choose to say it's a combination of their fault and the system sucks.
I will admit to you the system is TOTALLY fucking rigged but if you even ever so much as hint to the younger generation that they can cast blame instead of doing better, then they will fucking fail by leaning on blame as a crutch.
The shortest distance between two points is a straight line and the juvenile mind will take that path and never fucking ever look inward to blame, accountability, and most of all, growth.
Make excuses. Or make progress.
Progressives make excuses, while conservatives make progress.
People who blame themselves first will be way better adept at taking on a fucked up system then those who are most ardent to lay blame by the system first before even glancing inward.