It's an odd old field and it is clear that many make little or no return from their efforts. However, some things do work.
Form my experience and contacts: like @DarkRootsBlue says, there is virtual PA work. A good friend who is organisationally awesome has a part time PA job and does additional freelancing. It's reputational. A firm in a fix because someone has left, is away, or let them down, turn to her for a while and the wheels keep turning.
There are niche 'sexual services'. I assume they are grimy and not aligned with my values. However, I do know a contemporary who has clearly made a considerable sum from them. She knows I know and we have discussed it the once and now just don't go there.
Another friend has a brother who lives in Herts on Far East time doing something in Asian markets linked to UK firms. I truly didn't really grasp what he does when we chatted as it seemed improbable and dodgy, but it seems to pay off mortgages.
I do some freelancing occasionally, but it's very me based and linked to my knowledge and contacts related to trade and business risks with particular countries. It's for people who know me and trust that I can provide a sound confidential analysis and will pay for that.
Unlike all the above my Gran seems to have a continual Ebay throughput and makes very little from it for the effort she puts in. The process seems to please her though.