the reward for successful skunkworks at a large co is typically promotion (serious promotion to very high-paying, visible roles). That can be very rewarding for certain personality types.
(Serious question - what I have seen is that the team lead gets bumped up one notch and gets to try on a larger scale).
I know of at least one team that came up with something major that asked for their compensation to be tied to their product success having their idea moved to another team because "they should do it for IBM purely". Of course that product failed for lack of vision and focus.