+1 In any major city it's probably 90% chance they're either a crook trying to scam you out of something or mentally not quite right. The remaining 10% will be tourists or people from outside of the major city.
"Someday - and that day may never come" - they will be asking for something. Now you are on talking terms and it will be harder to refuse the ask, compared to the request of a complete stranger.
This is sad but not inconsistent with my experience. Though I think 10% is actually the people who genuinely want to have a nice conversation. and I think that worth putting up witrh the rest 90% for.
I understand what both of you are saying, I lived in areas where if someone is talking to you on the street theres a high chance theyre asking you for something, so you learn to just kinda block all of it out. Now that I moved to a smaller town, I find myself talking to strangers much more frequently.