Some developers have made half a trillion. Others have lost probably a lot more.
The problem with a closed ecosystem that capriciously removed apps isn't that you can't make money. It's effectively protectionism, with those allowed inside the walled garden having less competition and therefore an easier time taking profits.
I can't tell you how many conversations I've been involved in where there was discussion of, "yeah, but what are the chances this makes it through the AppStore?" and the answer is almost never 0% or 100%.
The problem with a closed ecosystem that capriciously removed apps isn't that you can't make money. It's effectively protectionism, with those allowed inside the walled garden having less competition and therefore an easier time taking profits.
The problem is the risk.