That is true, however this is not really relevant for buying a product. And an app that relies on ads where you can buy premium for $20 is just that in my eyes, a commercial product, and that is fine. But dividing the costs between all users to estimate a price is weird to me, that's not how market works and ignores offer and demand. This argument is nothing a potential buyer would consider when buying an app. And $20 is a lot of money especially in todays time. I don't think I have seen a price like that apart from really big commercial apps. But yeah if you want to support, do that, but consider spending money to your instance instead and using one of the other great apps available.

They do not value other people's time and also do not realize that everything on the internet is free because of advertising