Everyone loves to say startups fail because they run out of money. That is true but it is not the real story. Most startups fail because the founders fall in love with their idea instead of the problem they were trying to solve.
An idea is not sacred. A problem is. When founders treat their first version of a product as something precious they stop listening. They ignore the customer who says this does not work for me. They keep building the thing they imagined instead of the thing people actually need. By the time the money runs out the truth was already visible for months.
The startups that survive are usually run by people who are a little less attached to being right. They change direction fast. They kill features that do not work without crying about it. They treat their product like clay not marble. This is uncomfortable because founders are taught to sell a vision with total confidence. But confidence in the wrong direction just gets you to the wall faster.
If you want your startup to live longer fall in love with the problem. Ideas can be replaced. Discipline cannot.