Steam states in their EULA that your purchase a license to play the game but not own it

🤦

While what you say here makes a whole lot of sense please don’t mock people who get called conspiracy theorists as many conspiracy theories have been true over many years.

Do you live in an area with lots of homeless? That seems most likely who would do that. Or some mentally deranged person. Either way, be careful with those types of people.

You could try the photography/videography aspect to bring them to justice or the classic scare and/or beat them with a baseball bat