Pretty much every business is built on shaky foundations. If you never built business on shaky foundations, you'd never do anything at all. You needed an IBM-compatible PC to use Windows! You need a web browser to use Hacker News. Y Combinator is only meaningful as long as dollars are worth something.
If you make a business that runs on IBM PCs, make a few billion dollars, then 10 years later IBM rugpulls the PC line and sues everyone who copied it... was there really a "lesson" that needed "learning" or did you simply succeed at business and make a few billion dollars?