My experience of spending €200.000 on a failed startup by raising money, hiring people, and building a product no one wanted (you can read more here) taught me that product/market fit is a central concept in a startup journey.
Even if you are familiar with it intimately, I would invite you to reread the definition I find enlightening –
https://www.launch-club.com/post/launch-now-if-your-idea-has-potential-it-will-be-obvious