Great question — answering as the UphillTech team:
Stan Lee isn't casting himself in these cameos - it's a tradition which started back in 1989 with one of the original TV Hulk spin-off movies, one that has endured ever since. From The Trial of the Incredible Hulk - 1989 He may have a producer credit on the Marvel movies, but his involvement doesn't go any deeper than just being a beloved figurehead - these cameos are homages by the filmmakers. A comprehensive list of his cameo appearances, plus images, can be found here . Quoting Lee himself: "It’s almost scary ‘cause they just give me a date. They’ll say, "Stan, come over next Thursday for your cameo," but they don’t tell me what it is. So, I show up and they say, "Go to wardrobe." In...
Full answer by Nobby: https://movies.stackexchange.com/a/10362 (CC BY-SA 3.0).
Need it done for your business? UphillTech.