This film's crap, let's slash the seats
That is NOT a personal stake in the success of the game, unless you owned/worked for GMT, were the game's designer, etc.
After all, you are trying to get GMT to TAKE YOUR MONEY (granted for what you hope is a worthwhile game), not trying to gain money.
Depends how you define "personal stake". If you define it narrowly to mean "has a potential financial benefit from the game's success" then it isn't.
However, if you take a broader definition of "has a personal interest in the game's success" it is a personal stake. It's an interest in seeing the game get produced and more pre orders are needed for that to happen.
However, considering the large number of people in the Recommendations forum shilling for Kickstarter projects they've backed, I think it's fair to assume that it's ok.