all those homeless is incredibly generalizing, there's many reasons to be homeless. but the top ones are drugs and mental illness.

many are drug addicted, they would have somewhere to go but they opted out of society (well, they aren't in the forest so not full opt-out)

but yes a combination of state run rehab / mental hospitals seems to be the only solution, but is it done by force?

if it's not forced you'll have a hell of a time getting people to go. if it is, you are now rounding up potentially unwilling people and shipping them to a facility.