Successful companies have a 4th factor. Product, market, and founder fit are well-known. But a differentiated hiring source is just as important. The default-case for early-stage companies is to take whomever they can get. But a differentiated source gives you inside access to the right people, at the right time.

The easiest way is to hire your college friends. Nvidia/Netscape early hires came from Stanford/UIUC, respectively. A second way is to look where others aren't. Rippling hired over 150+ ex-founders. A third way is is offer outrageous packages. Alibaba let John Wu stay in Fremont to start his own team, with his own pool of employee options.

Yet the more successful you are the harder it is to maintain this source. For hiring college friends, people take less risk as they become more successful. It's easier to convince fellow ramen-eaters than people with mortgages. In the second case, eventually others see your success and start looking where you are. Many startups now have explicit ex-founder JDs. In the final case? Well, you can only offer so many outrageous packages before you go bankrupt.