On Day 1 of your PhD you have promise.
On Day 10 you might be worrying what you’ve let yourself in for, but you’re better than you were on Day 1.
On Day 100 you might be struggling, but there’s a path ahead even if you can’t see it.
On Day 1000 you’re doing so much more than you could at Day 100! Your thesis is taking shape, though there’s probably still a fair bit to do.
Well then: how good are you and your thesis going to be by the end? Pretty darn good.