It depends a lot on the product and the audience, but from my experience, you are never going to get results with your first $500 or $1000 on Facebook Ads, regardless your background. It takes a lot of trial and error just to
understand what works, and then some more to drill down, get better, lower costs, etc. I'd say you are looking at three months and several thousand dollars of experimenting
at least to start getting decent results, even with a strong PPC background. Facebook is just a completely different beast.
You can most definitely not set up your first campaign, pick the first targeting criteria that comes to mind, and expect good results with a positive ROI within the same day. If you don't keep at, it of course you are going to walk out with the idea that Facebook Ads don't work.
Source: Spent a six figure amount on Facebook over the course of two years.