People aren't stupid. Everyone knows that unless you are dirt poor, kicking a ~$100/mo habit in isolation doesn't do much, because personal finance is more complicated than that. Likewise, kicking a coffee habit won't necessarily make you much healthier, especially if you partake in many of the habits people don't generally find terribly detestable that are equally poor, like sucking down a liter of coke each day, overeating nearly every meal, hardly exercising, or drinking booze after work.
But humans are humans, and boy does the smug superiority of telling the entitled millennial that their bank accounts are empty because of the lattes and not the surprise medical bills, crushing student loans, car insurance, high rents, etc. seem to appeal to personal finance gurus.
Also, even if you're going to drink coffee at retail prices, you can have the kind that's under $2 rather than close to $5 (I'm not even aware of where to get that where I live).
You are reading your own comparison backwards to make this point. I'm sure $50K can make you $100/mo in perpetuity. Saving $100/mo does not give you a lump sum of $50K. It gives you $100/mo.
Viewing it another way, At $100/mo, that'll take 42 years and 8 months to save $50K. If we're talking about a higher yield account, let's charitably assume 2.0%, you could probably get it down to around 30 years.
Personal finance and health are both things that need to be viewed holistically. They're lifestyles changes. Having good overall posture is more important than individual decisions, and honestly, making more money trumps basically anything you could ever do to 'hack' your finances. You may as well spend less time hacking your finance and more time growing your career. Or hell, more time working on your health, something that you don't get any second chances to fix later on.
And let's not forget. The conditions that folks were making long-term investments in in the past are not the current conditions. The human race is facing seemingly-unprecedented existential threats and no doubt that is going to affect someone's willingness to make long term investments.
And, you know, even if everything else ends up fine, you could always just get hit by a bus tomorrow. So while you should certainly give a shit about your overall financial and medical health, maybe living in fear of spending $100/mo on something you enjoy isn't the best balance to life, realistically.
I'll just take the fucking coffee.
If you feel like they are different, that's not something to debate.
But people trade one for the other all day, every day. You mentioned student loans. If you have a loan, you got a lump sum up front in exchange for a series of payments, so why are you saying you'd have to wait 40 years?
There is no Latteholics Anonymous.
that beer is less healthy
than lots of sugar likely
fails to surprise
If you don't like gay marriage, don't get gay married.
If you don't like guns, don't buy one.
If you don't like expensive coffee flavored milk drinks, don't drink them.
Etc.