As well as the risk of relying on a business that fails, what happens if the business you're relying on succeeds? It feels like a lot of startups people discus

As well as the risk of relying on a business that fails, what happens if the business you're relying on succeeds? It feels like a lot of startups people discuss here are really just set up to give an 'exit' to investors through selling to a bigger company (at which point the product probably dies).