This can happen to the slumlord (who will then send someone to beat up the squatters), to the big capitalist (who will go through the courts and win) and to smalltime owners where that is maybe their family home or future retirement apartment (who will suffer the most).
Homelessness/lack of housing is a problem, but squatting is in most cases not the right solution.
Then starts a possibly very long process to have them evicted/ If they have a child you are basically screwed and won't be able to get your property back. Or you will wait months/years and get a ruin back.
Please give your opinion about squatting primary and secondary homes of people. Who worked to buy them and have zero rights afterwards, when a colony of parasites come and destroy their belongings.
This is what happens in France.