what if there were some permanent upgrades, so you won't have to keep rebuying them everynow and again. Or an upgrade that make some upgrades permanent, those upgrades would cost a lot of angels(so only the ppl that would get tired buying tons actually gets it) and could go as "make the firsts 10 upgrades permanent, makes upgrades from 11-20 permanent. and so on, and so on
 "AdVenture Capitalist"){kind=icon}