As a starting author, and this may be true about veteran authors, the first physical copy of a book can be a kind of wake-up. You look at it and think, 'I did that?', 'That's my name on the cover?'. 'Wow, this is me now; an author?'.
Some family came over this Christmas (Xmas 2020) and, on the way, they stopped by another family member's house. While they were visiting, a friend of the family took out a book and said, "Hey, I bought this book".
It's a little thing, and just the first of many but somehow seeing your effort in a tangible form really makes you think. I hope it's a good book and that it entertains and, maybe, makes you think a little too. I pretend, perhaps, that it will make a difference in this dark, dark world.