I'm looking at https://yclist.com/ (no idea how updated or accurate it is) and seeing a lot of companies are have been around for years and not dead or acquired that I've never heard of. I'm mostly referring to cos that have raised another seed or series A for a few mil and then just sort of lingered. I do not know of every 100 cos how many successfully raise another seed or series A beyond what YC provides (I would assume many do)