>The people who end up in truly dire circumstances have backstabbed everyone who ever trusted or helped them.
Or their family backstabbed them, if they ever had one (this article has a case study on someone raised out of an orphanage). Or this continually individualistic society has loosened support networks so you never truly got "friends". Or you simply got priced out because rent became 3k and you're not a silicon valley engineer.
Not all homeless people are drug users. Just the ones you remember most.