Some people might think "10-20x growth sounds likely for a startup, no?". Frequently, at "Series A" a startup is valued at $20-40M. Getting a 10-20x multiple on that means it should get to $200M-$1B range. Only 5% of all YCombinator companies hit that milestone (~100 companies from ~2,000 deals). Odds for a startups not backed by YC & co, would be lower. So no, not that likely, even if you're as early as day 1 of Series A.
You're comparing seed funding (Y Combinator) and series A funding - most YC companies have yet to raise a series A. The other thing is that most YC companies are young and still have time to grow.
I think you're comparing apples to oranges and trying to make a quantitative conclusion.
It's fair to point out that if a company gets to Series A, it is substantially de-risked. IIRC, ~30% of YC startups get to Series A, so this milestone is material.
If a yc co from 5 years ago still hasn’t raised a series A, it’s probably dead. (I would push this to “1 year ago,” but yc invests in long term projects now like biotech.)
