I think that many people "feel good" about rejecting others and some even do it to people that haven't expressed interest in them. I find the latter to be more offensive.
My strongest memories are from 3 different occasions.
On eHarmony, I paid $60 for a monthly membership and was matched to a man...he messaged me first. I didn't find his photo attractive, but I know that photos can be deceiving and we seemed to have a lot in common. I wanted to be open and thought that maybe we might click. Replied with a friendly message only to be proactively rejected with him saying he's only attracted to women that look like Emma Stone. I wasn't evening expressing interest...I was just responding to his initial greeting!
Another occasion...I was shopping at an electronics store and was looking to buy a music keyboard. The salesperson negotiated a lower rate for me but I wasn't looking to purchase that day. I asked for his business card and he probably thought he was doing me a favour and rejected me; stating he didn't want to give it to me and he has a girlfriend. Like wtf, I wasn't hitting on your rude ass, *******.
Most annoying of all...I was busy working at my cubicle desk and a colleague went inside and told me he was leaving for a new job. I congratulated him and he then said something along the lines that I should check out opportunities at the new company cause it's great. He then stammered and backpedaled a bit...clarified that he wasn't just saying it to me but to everyone. I felt he was concerned I would think he was interested in me. When he said that though, his smile seemed to widen. What an ass.
By some miracle, I'm not single anymore, but good god...if anything were to ever happen I wouldn't even bother dating or meeting people again. I hate people and wouldn't have the strength to go through it any longer. I empathize with you folks experiencing the pain of rejection and it's even more annoying when people go and proactively reject random uninterested people. I hope that you all find some luck quickly.