It takes ten years to build a successful company.
VCs are good at picking founders. So why do only two in ten make it? Truthfully, probably 70% of VC backed founders are capable of building a successful company on a ten year timeline. But VCs have their own investors, and VCs are expected to give 20% returns per year, at minimum. Their funds also have a timeline of 10 years. Which means that companies that would become successful in the average timeline are below the curve for VC expectations, and end up cut after only five years.
It takes ten years, but you're only given five.
VCs are still successful, of course, because two in ten founders are able to move faster than the timeline. Which means that 5 of 10 founders (the ones that are all likely to build a good company in ten years but aren't the top two) find themselves in unfriendly board meetings where they're challenged to show growth that isn't possible yet while their runway shortens. Those founders end up with unfavorable outcomes, and their potential is wasted because their timeline doesn't match the investment returns. VC portfolios are only 50% efficient.
Bootstrapping isn't any easier. It takes ten years! Now you've got the time, but not the money or resources. Most successful companies have been to the brink of failure. At least VC backed companies have cash to absorb short term losses. Bootstrapped companies may not.
Your choices are not wonderful. You either must outperform 80% of your peers or face an early death at the hands of investors, or you must be able to hunker down through 10 years of financial instability or face an early death because you starved during the seige.
I've seen a lot of great founders get hamstrung by the decision to go with VCs, not realizing how much better than average they'd have to be in order to be allowed to continue on. If you're one of them, if you just got out of a board meeting and are wondering what you did wrong, the answer is probably "nothing". It just takes ten years, and you don't have the time.
 There are many ways to define success, but I use "sustainable market significance" as mine.