And yes, it's actually very, very easy to do incredible amounts of damage to a place without much action. Don't clean it and leave trash rotting everywhere and cause an insect and vermin infestation. Throw literal shit on the walls, leave a clogged faucet on and forget about it and cause a lot of water damage everywhere along with a very bad mold problem, punch the walls in anger and leave huge holes in the drywall and broken windows. Rip off cabinet doors and use it as firewood because it's 'free firewood'. Fixing damage from bad behavior like that crosses into 6 figures very quickly.
And if your actively angry, you can do shit like pour concrete down the toliet and faucets and more.
These people need active management in a long term mental health facility, not just housing. The +%90 of invisible homeless that don't have a serious mental illness, brain damage and crippling drug addictions yes can be helped by housing. Most 'invisible' homeless people in that category get out within a year or two. I think what everyone is referencing when they are talking about homeless is the chronic visible ones yelling at a random tree.
We're talking chiefly people addicted to opiates, not someone affected by stimulant psychosis. They can handle homework just fine.
And even if that was the case, the cost would be lower than keeping these people in hotels and less damaging than sleeping rough.