This is an interesting conversation. Over the last few years I've seen a lot of people selling stock photos from their own websites and they seem to be doing quite well. The ones that I've seen, mainly focus on images for creative business owners and women entrepreneurs and they rely heavily on social media marketing to make sales. The owner of TwigyPosts has said that she makes over $100,000 per year.

Here are links to a few of the websites I'm talking about:
https://www.scstockshop.com/
https://twigyposts.com/
https://hautestock.co/

"seem to be doing quite well" -- but do you really know how much money they're making?

"The owner of TwigyPosts has said that she makes over $100,000 per year."

Good for her.

The actor Mark Wahlberg made $68 million dollars last year. So therefore all actors must make a lot of money.

The problem is that the people who are not doing well tend not to boast about how little money they're making. And other people who are doing well may not want to advertise the fact.

Photos on social media are stolen and copied.

In my case, with huge watermarks, just like from agencies, but their watermark is smaller.

Photos which have been legitimately bought and are on the web are also stolen and copied, but without watermarks they are attractive to a much larger number of non-buyers, and these are usually much bigger than I post to SM. I find much more of that sort of theft than 'lifts' from SM. YMMV.