I can’t count how many times I’ve heard someone say, “I know it still needs work, but I’ve gone over it again and again, and I just can’t wait any longer. I can hire an editor to go over it after I have some profits from sales.”
Not only is that foolish, but it’s just bad business. You only get one chance to make a first impression. In regular life, you might meet someone who makes a bad first impression on you, but who gradually rises to a better status in your eyes as you get to know her better. Perhaps she was having a bad day when you first saw her, and wasn’t acting in her typical cheery fashion.
In the book world, you’re not likely to have someone give you a second chance if the first impression isn’t a favorable one. The reader gave you a chance already and didn’t care for what she read. She may have paid good money to not care for what she read. She’s not going to give you another dime if she can help it, because she does not know you personally, does not have to interact with you on a daily basis, and owes you nothing. She may even insist YOU owe HER something: a refund for a not-edited, poorly written book.
If you’re waiting for profits to pay for post-publishing edits, you’re doing it all backward.