The problem with mining in the software business is that it doesn’t work. It creates broken, useless companies.
Founders and angel investors usually don’t particularly care if the companies they created live or die after they sell out, because they’ve gotten their money and moved on. There’s no stigma to having a company you founded fail after you leave it. In fact, again, it's a badge of honor: “Bob Smith founded Flopper.com, sold it for $46MM, then got out before it tanked! Genius!”