Earlier quoted context omitted.
30% is an insane amount.
Did you research Apple's costs for running the App Store, screening apps for security, etc., before making this blanket statement? I'd wager not.
Of course security screening is expensive, but it's also not that expensive (e.g. a typical software company might have a 10-30% profit margin, so in some cases apple accounts for roughly half the operational expenses of a company – i.e. the company pays as much, or more, money to apple as it does to its entire payroll)