Don't be so certain - if you add up the top competitors to the iPhone (just as expensive Samsungs, Huawei, etc), they're about the same amount as iPhones. Do these people not have disposable income?

The gap is quite obvious - because of the multitude of free alternatives on android, users are far more likely to not spend. The competition is way higher.

Developers want to destroy the walled garden but the fact is their product will be instantly devalued.