Buying a car directly from a stranger

Hello, not sure if this is a good place to post a question like this. I’ve been looking at used teslas for a while now and they’re finally getting down to a point where I’m happy with the prices. I like some of the deals I’m seeing from people in facebook groups and other random sites, but I’m wondering why I should, or should not buy directly from another stranger.

What are some things I should be worried about where I could get screwed here? I mean the obvious problem is I could find a car in a direct purchase for cheaper than going through a dealership, but it isn’t clear to me what benefits I’m getting from a dealership that I might miss out on. Are there protections in place or something where I shouldn’t consider buying from someone random online?

If you’ve ever purchased a car directly from someone you didn’t personally know prior please let me know how that experience went as well.