Read the quote above, basically there is a bug in multiplayer valve source 2 games (idk if goldsrc is included) where people can have access to all of your shit in the computer, please do not play valve multiplayer games until we get a response from valve that it is all sorted out.
Another quote about this situation: https://steamuserimages-a.akamaihd....701/2964A23C859723E5955CC3ABF04952310DA6F2AA/
given by @Frundley Scuoot, basically it says that we shouldn't panic about this situation, I kinda believe it but I'm scared for my shit to be stollen, so yeah I won't play any source 2 multiplayer valve games until this shit is gone.