lol guess who's going to die at the start of your game? (theoretical spoiler?)

That's merely one slice of the new market. There's also rando gamers who really like X actor and may check out the game as a result. Is it a huge, bankable chunk of the market? Probably not. But that's really the only reason to try and get big name talent for your game to begin with, apart from maybe the devs themselves being fans and wanting to work with said name. If SuperMac really likes Clancy Brown, then yeah, DadRyder will probably stick around a bit

When ESO came out I was seriously considering checking it out because they got not only Kate Beckinsale but Bill Nighy as well to voice major characters. Of course, the game turned out to be shit (at least at launch, some say it's gotten better) and they probably phoned it in (I checked out Youtube clips of them but nothing memorable stood out) but still, probably the only reason I was even considering it was the big name talent. I'm a fan of TES but not MMOs so they would've needed something like this to entice me.