Our general rule is if the product doesn't have broad appeal, you don't run it on FB.
My running theory on all ad networks is pretty simple. There are a very small subset of users, 25%-30%, of people who are regular purchasers and these companies know that based on conversion data. They generally just throw your ad in front of these people and let it ride.
While sure it sounds like you were ripped-off, I would expect that just about any mass-market medium offering ad-targeting to "senior-level engineers at technology companies", "senior managers", "wealthy yachting enthusiasts" or similar super-high-value clients be a ripped-off if it was offered. I'd imagine anyone in the position would avoid anything that could target them with ads (blocking ads, going incognito, avoiding social media, etc)because otherwise they'd be continuously barraged by companies.
Here's a specific example: we ran around $1k in ads last year, targeting senior-level engineers at technology companies, but the ads were getting liked by mostly people who worked minimum-wage jobs. Twitter and LinkedIn targeting were fine with pretty much the same parameters.
This is one example, obviously, but it's so trivial to see that targeting is almost completely uncorrelated with reality, that it's not hard to come up with more examples.