Housing is incredibly expensive these days, and there's really no way to make that cheaper other than live someplace terrible or spend hours and hours extra commuting. Both make huge differences in quality of life.
I'm sure there are many people throwing money away for no good reason, in fact many of those people are rich. But at a certain point you just need more income.
From my personal circle of friends, the people that I know that own the most real estate are people who are disciplined (think accountant in a 500 Fortune company, or an engineer working for Boeing, or a web developer slinging some internal Asp.Net website at some company you never heard of). Meanwhile some guy working at my current huge-tech company sold all his stock when it vested and "invested" the proceeds in options... He was taking uber to work even though you can show up anytime you want (maybe take the bus? maybe some days you work remotely?) and he was complaining to me that he will never be able to buy a condo...
Well, since you saved it by excluding a lot of pleasurable spending, you can't really count it as "fun" money and therefore it's not that great, really. With the current market, it's also not nearly enough to get you anywhere near buying a house or an apartment. It can be used for a car, but then again, is a car a better investment than nice coffee and food?
While I do see the value in saving and I get why spending this money looks wasteful, I can also see the other side of not bothering pass on convenience for a bit of extra money. Of course, it all depends on how well you're set up generally (i.e. if you don't have an emergency fund, those 4k$ are a lot more important).
We're talking about kicking a vaping habit, not eating out or doing food delivery four times less a week and making your coffee at home. Its not like they're now no longer doing anything fun in their lives.
Saving only that for 3 years and you've got over $13,000. While not a ton of money, $13k is more than enough to qualify for a down payment on a small house or condo in many housing markets in the US. Sure, probably not NYC or LA or SF, but doable in DFW, KC, San Antonio, Houston, Oklahoma City, Cleaveland, Rochester, Syracuse, Utica, Philly, Wilmington, Tallahassee, Corpus Christie, Albuquerque, and more.
I'll take your $16/wk for vaping costs, I don't have any hard data but I think that's probably a bit low.
$5 for coffee 5 times a week, that's $25/wk.
Looking around me, its hard to get a meal delivered with a food delivery service for less than $18. Making a meal at home, even a frozen pre-cooked dinner, is usually like $5 or less, so we'll say an additional $13 meal 4x a week so $52/wk.
52 + 25 + 16 * 4 weeks in a month is $372/mo. Over $4,400/yr, on just eating out/delivery, one coffee 5 times a week, and vaping. And somehow I doubt its really just 5 coffees a week, its probably not just $13 additional cost per meal only 4 times a week, I doubt a vaping habit is really only $16/wk.
Is an extra $4,400/yr in their budget a big deal to the people in question?