Across 5 funding rounds, Crunchbase lists Loopt as having raised $39 million and then was acquired (acqui-hired?) for $43 million. He didn't create any multiples of value for his investors. Loopt wasn't a breakout hit like so many other YC startups have been. It was certainly one of the first interesting location-based apps in the App Store, but soon was surrounded by other location-based apps and never really appeared to surface and gain traction.
Obviously Sam runs YC now and has dramatically improved it, but in the lens of being an entrepreneur, isn't he still essentially unproven, and not a success story in the startup world?
My belief is that there's a large chunk of building a company that I will never learn or understand without becoming a founder myself. Maybe that's 50% of success. However, for the other 50%, I can actually learn things better than many founders because they have a sample size of one or two or three startups that they have started, while I can look across fifty or a hundred companies that I am intimately involved in and analyze what is different between the ones that become huge and the ones that do not. I think this cross-sectional pattern matching is what makes a lot of VCs and investors sources of good advice (in some startup topics) even though they might not have built huge companies themselves.