The GitHub founders spent 5 years entirely bootstrapped before taking any outside investment. IIRC, they spent the first 2 without any employees, doing all coding, sales, and evangelism themselves and making barely-pay-the-rent revenue. Their salary had they not started GitHub would've been roughly $300K/year. That's close to a million each in opportunity cost, with no obvious indication they'd be successful at the end. (They were themselves early employees of PowerShell, working for startup salaries until it was acquired by Microsoft. They chose not to continue working at Microsoft after the acquisition.)

Methinks you need to distinguish between startups like Theranos, Clinkle, or Juicero, where a well-connected and charismatic founder meets an investor who takes on all the risk and then they crash and burn spectacularly and nobody gets their money back, and a bootstrapped team of engineers that build a product millions of people want and then get handsomely rewarded 11 years later.