Get Rich Quick scheme:
1) Identify existing service selling out their users. 2) Copy service, but remove all tracking and put all engineering and design effort towards an amazing user experience. 3) Charge low, but sustainable fee directly from user. 4) Control costs. Single digit number of people, working remote et cetera. 5) Either wait for the tracking/ad-model apocalypse and subsequent rapture or profit directly when bought by Apple.
There’s no need to wait for a eureka idea for a service; there’s so much out there ripe for the taking.
Execution. Empathy. Ethics.