Actually I'm a student living out of home primarily on government assistance, with a casual job. My parents have never supplemented my hobby in any way.

Over the past 3 years I've assembled UR Delver, Storm and Burning Loam, I have 11 duals (6 blue), sets of forces, snapcasters, each fetch except Flooded Strand and Marsh Flats, each cantrip, and DRS, and still had the money/cards to build three Modern decks.

My means have nothing to do with what format I play or what decks I play, if you care enough, you'll get off your ass and save what money you can, make smart investments and smart trades and eventually get there.

Those "responsible adults" you know either don't care enough, or aren't responsible enough. If you're buying takeout 2 nights a week, you're foregoing a set of DRS, or a Khans Fetch a week. If you're buying boxes of standard rotation sets, you're foregoing a 2-3 non-Blue, non-Bayou duals, or one blue dual a quarter. Its simply a matter of wanting it enough.

EDIT: If those adults have kids, I'm not saying to neglect their needs, but that's still a choice of theirs (to some extent), and they're probably making the right one.