Of course it changes depending on who you are and where you are. If you’re sitting in a cafe you can tolerate people in you intimate space. People in wheelchairs are always sitting down so its different for them. It also depends on what your willing to put up with. No one would want to be 'high maintenance' but I am unwilling to feel someone else’s body against mine…
I have never given much thought to ‘personal space’, which seems an exclusively American phrase. The rest of us just have to cope with it lol! I never like rubbing elbows with ‘the great unwashed’, but most of the time I find it tolerable.
Criminals feel confident because they are on the offensive and they can attack without warning, but when they attack me they enter my domain because I am ready for them and know what I would do. Yes, you can never be sure of people’s intentions, what I like to call an unknown quantity.
Proxemics as seen below show the commonly agreed personal space.