Hello. This happened today, but people in general making fun of me has been a recurring theme throughout my life, and I'm a sensitive person so wonder what is wrong with me. So. I was at the bus station sat next to some 30-ish looking guy who offered to exchange money into larger coins, when he saw me fumbling with change. He seemed eager to chat and spoke at length about his life, even though he didn't care whether I offered much input or was interested. I did try though at the beginning. We had a "normal" conversation for about 15 min. He also said he received injection "therapy" today, and I presumed it was something like an AP (antipsychotic), and I was right. He also seemed a bit spaced out or not with it.
He asked how long I ever worked for, and I said barely a year (due to my own mental health issues I didn't feel like mentioning), and said it was because I quickly got bored and constantly felt something better was waiting for me, so switched jobs a lot, and that part is true.
From then on, he started smiling or chuckling weirdly, and kept asking weird questions. Like if I read books much (chuckling plentifully and even when I was silent whilst looking at me - definitely in a mocking way), if my surname is a famous singer's surname (we share the same first name) but that he "doesn't know her", if I believe that he lived by himself when he was a small child for a year, etc. Laughing all the while, directed at me.
Even when I tried to respond, he was sort of making fun of what I said. Not being too sensitive, was very uncomfortable for over 10 minutes and he kept looking at me and laughing at me.

So my question - someone with his sort of experience/problems, why would he randomly start making fun of someone? In your exp., what is "wrong"/different with someone (child or adult) who is often made fun of? Always wondered this. Or why would someone do that? This sort of upset me and it's not a nice feeling, from a stranger. Don't think his "illness" had that much effect.
Sometimes I really think that my few friends never do this or never can tell me what is wrong with me because they're too polite or tolerant.
What is your opinion?

Also, he was sober and fine-fuctioning, was definitely not having an episode during the talk, was just a little off due to recently receiving therapy.