it's not that this guy is spending on experiences instead of things -- it's that he's using *other people's things.*
I don't see any problem with that. The house is a resource made available to him, it would be a waste if he didn't utilize it and instead rented or bought a place for himself. His parents have every right to kick him out or make him sign a lease, but they didn't--and that's on them. Don't blame this guy for making use of what's available.
I have a similar situation in my family. My uncle owns a house with several extra bedrooms, and my millennial cousin (she's his niece) who earns a good living as a CPA is renting one of those rooms at a generously low rate. My family knows that she could easily support herself, but they see the clear financial benefit in letting her use the room. In fact, when she expressed interest in buying her own house, everyone encouraged her to keep her options open and continue renting the room.
Furthermore, my father recently retired and wants to move into that same area so that he can be closer to his ailing parents. He also wanted to buy a house, but we all talked him into renting one of the rooms in my uncle's house instead.
So, my point is that this living arrangement is a perfectly rational, financially beneficial decision for the guy in the article. The fact that he happens to be a spendthrift is completely unrelated to his living situation. Criticise him for his spending if you want, but that's missing the point.