Note that following the lean startup method does not itself guarantee success. I know at least a half dozen founders who have followed the Lean Startup method (several of whom were actually in Steve Blank's class at Berkeley), and in all cases the result of their 100 interviews was "Welp, nobody wants that product." Which I guess is preferable to investing 3 years and $15M in venture capital into it, but it also doesn't get you any closer to a successful startup. (When I followed the Lean Startup method myself, it was actually worse - our 100 interviews said "Yes, we definitely want it", we built it, and then nobody used it. At least I took every engineering shortcut possible to build & validate it quickly and didn't waste time making it bulletproof before people tried it out.)

Also interestingly, a large number of gigantic corporations today did not follow the Lean Startup method, and arguably weren't trying to found a startup at all. Apple, Google, Facebook, E-bay, Dropbox, AirBnB - they were founded because their founders were curious and trying to scratch their own itch, and it turned out lots of other people had that itch too.

If I had to distill lessons learned from about a decade in startups (7.5 years founding ones of my own and 2.5 years working for other people), it'd be "Trust my emotions more, be curious, and quit trying to found a damn startup." The problem is that you need to judge new ideas emotionally rather than rationally, but when you have the "I'm going to build something awesome and get totally rich" mentality, it distorts all your emotions. Better to get rich by working in finance or for a FAANG, reserve some time on the side to explore, and only set out on your own when there's something incredibly exciting on the table.