That's routine cost of business. Humble Bundle takes 25% of sale revenue, just for the distribution and marketing, and companies are queuing up to work with them. Steam also takes 30%. Both of these are for software you run on your computer.

In fact Steam kills the whole "Apple store is a gouge" premise stone dead. It literally is just a distribution mechanism on desktop computers, where you absolutely can side load apps and games as much as you like, and they're still considered very much worth 30% by the market.

There's a reasonable discussion to be had about side-loading on iOS, that's a separate issues, but the idea that the App Store cut is unreasonable in the market is clearly bogus.