I was just sitting at the mall taking a break from mall walking. A man walked over to me when I wasn’t even looking up. He said "I haven’t seen you here before. " I said I wasn’t really here to talk to people and got up and walked away. He said he would leave, he may even have said sorry. I said I was ready to leave anyway. In retrospect I think he may have just been slightly mentally challenged so I wish I had been a little softer, he did not turn out to be aggressive. Looking for suggestions on something still clear and firm but more polite? This scared me for some reason, I think how fast he walked up and sat down near me.
Editing to add a key detail, he sat down close to me which is probably what made me more nervous than I would have otherwise been. I appreciate all the thoughtful feedback I’ve gotten and interesting discussion.


or real life expereince with people like the OP have taught us it’s not worth it.
Frankly, I don’t want to interact with people who assume I’m mentally ill for being friendly to them. And where I live at least, that’s the way a lot of folks react to friendly conversation if you are like standing in line with them. they act like you’re trying to assault them.
Then they go on reddit and lament how body wants to be their friend… well because you reject anyone who tries to be friendly to you and you mischaracterize them in your mind as some terrible person.
and it’s very aged based. I have a dog. people over 50 have no problem petting and asking me about my dog. millennials and younger folks, are like visible anxious and paranoid about interacting with me and asking me to pet my dog. I am also a millennial, I do not understand any of it. But I’m not on social media and I barely use my smart phone for anything other than phone calls and email, so I understand I’m an outlier in the way I interact with people. People my own age think I am weird for not wanting to text, and think my preference for phone calls and face to face interact is ‘demanding’.
Don’t assume of other people, and you’ll think less about thinking less of them. I get ignored most of the time, but that’s the game isn’t it. I secretly know you’re a human down there, even if you want to act like I’m not here. Let’s see just what I can get away with - sorta thing.
I don’t assume. I observe and I listen.
The problem with a lot of folks is that… they are massive massive hypocrites when it comes to this stuff.
And they catastrophize ordinary harmless interactions into these hyperbolic experiences in their head and make insane conclusions about absolute strangers who gave them no evidence to support their judgements. I also encounter it a lot when dating too. I meet strange women and they start lecturing me about myself… when they know absolutely nothing about me. But the weird fiction in their head they have already written so intense and real to them, that often they totally reject any real facts about me that don’t fit the story they have already made up. Especially the past few years I had so many expereinces where people tell me about myself, and I go ‘well that’s not true, I did x instead of y’ and they go ‘NO, YOU’RE LYING I KNOW YOU DID Y’. And weird shit like that.
I wonder if OP has legit dealt with mentally ill folks at all. I have. They don’t act polite and respect your boundaries, they get up in your face and scream and threaten you. And usually fixate on something bizarre. Last time it happened to me a few months ago it was a guy on the subway who started screaming at me about my boots being gay and how he wants to fuck me because they are so beautiful.