Yeah, I've often wondered about that too when watching build videos etc. I wouldn't dream of building to wait indefinitely for a video card—"indefinitely" because who knows when they'll be affordable again, could be a year yet.
All your other parts will be 6-12 months old by then. Why buy now, when there'll be newer or cheaper whenever you get the GPU, and they'll have full warranty?
Obviously if your PC dies and it's not a simple fix, then you have to do something. But otherwise, wait.