I tried Upwork a few years ago and didn't bother again after getting a bunch of clients asking for cheap labor. I'm sure there are great clients on there who pay fairly. I just have work already and was fine with just letting it go at the time. I've heard similar stories about Fiverr.
There's nothing wrong with continuing to try though. It's up to you how much effort and time you want to put into finding good, well-paying gigs on there.
Thanks for sharing your experience with us! Sorry this happened to you. I hope you have better experiences going forward.