Do you blacklist other book retailers by opting in Amazon’s KDP Select program for 90 days/minimum? The treasure chest of funds available to KDP participants – is it fool’s gold? Is the Select program a way to boost your sales? Is the name ‘bestseller’ that important to you even if it comes with a royalty check for pennies? Is it worth the risk of giving away potentially tens of thousands of your book for free? Is it worth the risk to see what happens and possible make tens of thousands of dollars? If the book is that good, will it not sell itself? Can Amazon help you reach your goals.
Some people LOVE the program and some HATE it. Different experiences for different people. The choice is yours to make. Just know the playing field as it relates to your goals. Finally, if your book sucks, it sucks no matter who sells it.