And if you had 5, 10, or 20 squatters... how long do you think it would take one jerk to ruin the place top to bottom.
Squatters don't need to be all bad to destroy properties. Only a tiny percentage of them have to be destructive, and then building will look like a hellhole by the time the owner sees what's been done.
You have made some logical errors here.
The fact that there is a hole in the wall is not ascribed to squatters and could equally be attributed to general disrepair.
I accept you might say: "there has been at least some crime, so there has been at least one criminal"... but you still don't know if that one criminal was a squatter or how many squatters there were who were not committing such crimes.
In the end, this anecdotal/circumstantial evidence teaches us nothing.