Reasons why most single people are single: they put zero effort into actually meeting new people and/or never actually ask anybody out.
All this "Woe is me I'll be forever alllloooonnnneee!" BS while sitting at home all day on the computer? Or going out but avoiding all possible conversations with strangers? Yeah no shit you're alone.
If you actually want to meet new and interesting people?
That's it. Maybe you meet someone interesting and single at this new group (and you already have a common interest). If you don't, make friends with other people. When you are single and have lots of friends people tend to introduce you to people they think might be a good match.
But all these people who think they have "social anxiety" because they aren't comfortable walking into a room of strangers and instantly being friendly? Congratulations, you are the same as almost every other person. People ask me all the time why I'm so confident with stuff like that - it's because I get exactly the same feelings as them but I've learned that the faster you ignore them and just go talk to people, the faster you realise that they're all just people too and in a few minutes you stop worrying about that shit.
Do that for a while and you just skip over the feeling anxious part, because you know that you can just go introduce yourself and have a chat with people. Some you'll like, some you won't. No big deal. But the more your do it the higher the odds are you'll meet someone you're interested in romantically.
Then? Ask them out! For coffee/dinner/whatever. If they say no, move on. Don't bloody dote on someone uninterested for years, it's waste of time.
TLDR: Actually try and you'll find it's not as hard as you think.