You can't distribute an iOS app outside of the App Store (outside of the enterprise). So Apple's 30% fee is essentially a tax on iOS apps--there's not a way around it.

Apple can destroy your business by changing a rule that makes your app ineligible for the App Store (or at least unprofitable, most recently seen in the whole in-app fiasco). There's not a way to distribute outside of Apple, so if Apple doesn't want to distribute your app then you have no business.