I think people are going to be weirded out by someone hitting on them at a business event.
However, I should note that as a technical cofounder attending these events, I've been approached and flirted with heavily by single female entrepreneurs who have ideas they haven't started building yet, who seem to be looking for a convenient all-in-one package of "a boyfriend who's also an entrepreneur, who can 'yes, and' my ambitions, and who has enough skill+experience to actually build the tech side of the things we imagine together." I'm neither single, nor a free agent business-wise, but some people can be both very pushy and presumptive.
The first step is always getting to know the other person. Hitting on the other person with romantic interest from the start is a sure way not to get to know them in a low pressure environment. If you get to know the other first, they also get to know you. Typically you'd be searching for someone you are willing to spend your time with, and who is willing to spend time with you. And this is only a feasible endeavour if you know them and they know you.
That means: Your goal is not to find someone to "hit on", your goal is to get to know people. You can still explore if the other is interested in a little bit more, once it is established that you find them interesting and they find you interesting.
Re: concerts and libraries, you meet people outside of them (for concerts, in line for them, or in the pit waiting for the show to start), not at them per se.
I don't know about "hacking camps" (hackathons? code boot camps?) — never been to one — but a close cousin of these, [industry niche] startup events, tend to attract just as many business cofounders as technical cofounders; and the business cofounders tend to be an even gender split. (They also attract seed-stage VC scouts and marketing people, and these jobs actually tend to lean female.)
> As I said, I do, but none of the things I like involve enough people of the opposite sex.
So... take up some new hobbies?
And when I say that, I don't mean to work "bottom up" starting from what you might like; but rather, "top down", starting from what hobbies your ideal partner might have, and then filtering those for which ones you feel at least amicably neutral about. E.g. if you feel like you'd enjoy being with someone who's also 50yo and "creative", and you're not against e.g. painting, or pottery, or creative writing; then attend a continuing-education course on one of those. Because that's where you'll find other 50yos trying to learn those things.