I suppose it is hard to approach people by yourself, but the particular group of people you mentioned sound sorta snobbish; I mean, who goes in an anime night and doesn't want to share their passion with others, even strangers? It sounds off to me.
weird. Anime's such a niche interest in the first place, you'd think they'd be glad to find someone who shares it. And seeing as you sound perfectly polite, and friendly, I can't see any good reason why they'd act like this. 7th child is right, I think.
I definitely have had somewhat similar experiences, and I'd say it's trial and error to a certain extent. Of course, if you're lucky enough to spot someone who is (like yourself) alone, you might have a much easier time. When people are already in a group, they can feel settled in. They don't necessarily want to change anything.
One thing: Perhaps the staff at the bar could help? They may know if someone else, or some group, would be interested in you. Nobody would know the bar and its denizens like they would, so they might be the ones to ask. Who knows? Perhaps someone just like yourself has been coming in on a different night, and you just missed each other.
I feel that being alone is better than being together these days. Is it the power of habit at this point? Maybe it is.
. Nothing wrong with it, of course. Sometimes we need time to ourselves, and who has any obligation not to be single? More power to ya. Long as you are fulfilled in yourself and what you do, most important thing.
P.S. Is "radio gaga" a Queen reference? If so, kudos to you, 7th Child, for promoting the best band on earth.