Maybe it's because I've only ever bought stuff on FB marketplace instead of selling most of my stuff there, but I've never really had much of a problem with it. Everyone's super accommodating, and super nice every time. Especially when their stuff is free, I've gotten like 3-4 CRT monitors from there, a sick huge bean bag with the memory foam, an old IKEA tv stand from like the 90's or early 2000's. I dunno. If you're really that nervous, just meet up in a public location, and make sure you're packing heat, it's not too bad.