Value generating product/business

I have been reading some books on why value value. I am really curious to know from some folks here, who have launched any product that got some customers to pay them, on how did they come up with the idea? How much analysis goes into it. What does it take?

Sorry for a lot of pressing questions there but I built some apps and got literally no one to purchase or pay for them. I am wondering if there is something fundamental I am missing in coming up with idea that customer care for.