@ OP,
please don't be too quick to read-into the outcome of such isolated incidents so personally and draw such conclusions. It's probably not that women don't like single guys, it's all the other reasons that have already been raised here.
Your focus determines your reality. So if you have already determined that women are only XYZ, then your mind will only search out to prove that theory correct. Even if women are ABCD, you won't even notice them. Instead your focus will only be on XYZ.
And chances are there are just as many if not more women out there who believe that men don't like women who hit their 40s, when in reality there are a ton of suckers who are willing. Just they have convinced themselves that they are already ineligible from the outset. So they don't even give the other person the opportunity.
Totally agree. Isn't this what they call confirmation bias? This pattern of thinking is very common amongst those are feeling insecure or have anxious tendencies.
Young women don't necessarily despise single men. Many more helpful explanations regarding that experience have already been given.
Regarding 'women only want the popular/alpha guy' naratives;
I would be careful about buying into that too. It's common for some people to project their frustrations with their interactions with women, or their single status onto this, and to identify with this narrative. A lot of the PUA evo-psych drivel is doing nothing more than capitalising on this. It's not as simple as 'women want the most popular, most powerful'. This sort of thinking can be pretty destructive thing to dwell on.
Regarding fear of being judged for being a loner;
Can't think of any logical reason, apart from the fear that the loner might try coming onto you, but even so, there's rarely any grounds in reality. Still, I don't think it's worth dwelling and ruminating over whether people dislike loners or not. If people are like that, are they really worth knowing anyway?