Who was it founded by? "A group of friends", the website says.
Really high production values for that.
I wouldn't be shocked if this was well funded.
Edit: did some digging. They have a Wikipedia article. https://en.wikipedia.org/wiki/Don%27t_Pay_UK
There's lots of press, too:
https://www.telegraph.co.uk/news/2022/08/10/dont-pay-uk-camp...
https://www.theguardian.com/world/2022/aug/09/tuesday-briefi...