I'm in another awkward position...

Sorry these happen often online, I guess. :/

Anyway, I have a mutual friend, he recently started messaging me because we both are diagnosed with schizophrenia. He seemed nice enough, but eventually he started telling me how "beautiful" I am and wanted to voice chat.
He's seen pictures of me online, but I haven't seen pictures of him... So I asked and he sent a picture.

He claims to be three years younger than me... But in his picture, he literally looked to be about 35. For lack of better words, (and sorry if I seem harsh) he was not attractive to me. He also told me that he has two children, which, I was DEFINITELY not going to bother with.

We only talked for about three days and he asked me if we could have sex if he ever came to California and I was like, "Ew. WTF." I didn't actually *say* that to him, but I was extremely creeped out. I DID however, tell him that I only had sex with people I knew in person... He looks like my ****ing uncle... and he had the nerve to ask if I'd have sex with him!? AFTER ONLY TALKING TO ME FOR TWO DAYS?!

What's wrong with men online?! Seriously... I don't want to talk to him anymore, but I don't know how to... tell him that I'm not interested in him? I don't respond to his messages with more than three words. I'm thinking of blocking him, but we are both in the same server, so I don't know if I could do that stealthily.

I ****ing HATE when men start off a conversation about mental health, seemingly being supportive and understanding, only to start "flirting" (or some form of flirting?) with you...

It doesn't make any ******* sense!

Sorry, I'm a little upset because it feels like every man I meet (mostly online, but IRL too) only wants sex from me or to take advantage of me because I have schizophrenia.

Is there something I am doing wrong that's attracting these creeps to me?
Is there any way I can change this?