I'm more referring to the wider audience, the people who will see Gary Oldman in a videogame and think 'I should preorder that'. They'll be interested, but not enough to buy a gaming PC just to play SQ42.
And if you aren't able to convert those people, I just don't think hiring a cast like this is economical.
I think you could call 90+ million crowdfunded a wide enough audience.. SC is already more successful than most games out there. So why is it even some sort of criteria to go wider to unlock some unknown milestone of unknown worth? What is the reasoning behind this?
Anyway, many of these actors are Roberts' friends or part of his network, some of them even starred in his previous Wing Commander games. The cost of hiring them is most likely a lot less than you think.