That's how it is with investing. It's always easier to see this sort of thing in retrospect. I'm still kicking myself for not buying Google's stock when it went IPO at $80. It's only gone up by a factor of ten since then. My reaction at the time was obviously way off, "Seems overpriced." Oops.
I actually would have bought in but my reaction at the time was "Fuck me, I'm a highschool student with no money"
You had better instincts than I did then, at least. Oh well, I managed to at least buy a few shares of Tesla back when it was $30 earlier this year, so at least I'm not calling them all wrong. I'd have bought way more than three shares had I known that it was go up by a factor of five in less than a year. It seemed like a good investment, but I didn't know it was THAT good an investment.