I used to work in an ad-tech company focused on mobile cpi offers that for several months paid the salaries of everyone involved by injecting malware in cracked apps on several third party app stores (they were making a profit out of it enough to dedicate a team only for this).
They even managed to automate all the process of "selling" cracked apps on third party stores. It is amazing how easy it is to trick broke 13yr old kids into installing stuff on their phones.