Great read on why startups fail which can also be applied to products. https://longform.asmartbear.com/avoid-blundering/

#1 on the list

Didn’t talk to customers (and listen)

If you didn’t talk to customers before you started, and especially after you started, that’s a blunder. If you talked to them and weren’t honest with yourself about what they were saying, that’s your faulty analysis. You should have used the Iterative Hypothesis Method or some other reputable framework.