How can you actually think you are qualified to have an opinion
here after visiting part of a city one time?
Well, you know what they say: "Opinions are like assholes. Everybody's got one and everyone thinks everyone else's stinks."There's very little data in these comments. Lots of anecdata, and I'm presenting an alternative perspective with my anecdata, but until there's actual data in the discussion, I'm not sure that we should be dismissing someone else's opinion out of hand.
From the context: parent said "as a European who has made some trips to America but never been to SF in particular", so I thought it appropriate to reply with my experience as a European who has been to SF in particular. My experience there was simply my experience: I didn't observe the antisocial behaviour being described, so it's fair to say that it's not common behaviour (in the areas I visited).
That's not to say it doesn't exist, or that it isn't more common elsewhere in SF. That said, homeless people do tend to congregate in areas where tourists visit, so you would expect the density of homeless people to be highest in those tourist areas, and for those places to experience the most severe issues.