"Waaaaaaah I can't play a game I haven't paid for yet a week before it goes live waaaaaaaah" Deal with it or cancel. I'd rather you do the latter, to be honest.
Yes, because you paid in full already totally means everyone else has already done so. I could've sworn I pre-ordered from Amazon and haven't paid a single penny yet, but I guess you know best.
The terms were never changed. You were never promised to be in on the first day. Never. Please, I encourage you to cancel your pre-order. People who plan on enjoying this game don't want self-entitled brats like you playing.