I remember my first book. I spent freakishly little time working on the cover, blurb, keywords and promotion before publishing it, because, well, who needs that shit, it will obviously sell itself! So I published it and opened my newly minted Amazon author metrics page daily as I waited for it to take off. I waited, and I waited, two months I waited and not one sale! three years later I have sold a few dozen, though it does seem popular at the local library.
This is how I learnt why marketing and promotion (and I guess luck) are everything and without being an influencer or spending money to get it noticed the algorithm will forever ignore you. Great to see these amazing marketing theories but you need to get noticed first.