I develop apps as well. Apple provides the platform, the users, advertising, user friendly rules that promote spending, the store, delivering updates, etc. last I saw iPhone users spent significantly more money than Android folks. You may want all of the same functionality without paying for it but you are not entitled to Apple’s technology. So you can either pay for their services or you can roll your own. How much time and effort and cost will it take to replicate all of that? Again, the claims that 30% is robbery is inconsistent with the far higher prices developers had to pay pre-Apple store. That didn’t come with auto updates either.