And that's where the problems begin.
You are seeking your validation and happiness in the wrong place. The validation and happiness must be almost entirely focused in the creation of your work and the opportunity of being able to put it out into the world.
What happens after that is anyone's guess.
You might be an amazing platform builder / marketer / social media star who launches an incredible campaign and end up selling a gazillion copies in a few months. Then again, you might end up selling a gazillion copies and then be ridiculed online for years afterward. Or your amazing media campaign might fall flat and go nowhere.
You might not do any marketing and get noticed by a publisher. That same publisher could make you the hottest writer in the world or they could screw you over with a cut-throat book contract.
You might do minimum marketing and build up respectable sales. You might to maximum marketing and have no sales at all.
Your work could end up wallowing in obscurity your whole life and be discovered only after you die. You work could bring you fame and riches in your life and then drift into obscurity after you die. Or your work could be obscure forever.
The possibilities are endless. In the realm of self-publishing, anything could happen. Anything. It's chaotic and unpredictable and it is precisely for this reason that you should not peg notions of validation or happiness on the success or failure of your book in the marketplace.
Validation and happiness must be almost entirely confined to the writing itself. Look there to find your happiness. That you have the chance to put your work out onto the market is a merely an added bonus. After that, be ambitious, strive for whatever notion of success you desire, but for God's sake don't let rankings or sales or media attention be the measures for your happiness.
I guarantee you will be setting yourself up for a disappointment, even if you surpass your wildest expectations in terms of success.