Those who were around during 2017 or perhaps even 2013, why aren't you a multi millionaire?

There seems to be this sentiment in crypto that people are sure BTC will go parabolic some time after the halving and then alts will follow and sure enough this has happened during each cycle.

Assuming you got into crypto from hearing about the hype during one of these cycles as most people do and made the typical mistakes of buying high and selling low during your first bull run because you got in a bit too late. Now knowing that the cycle will repeat in 4 years' time, what factors prevented you from going all in on the next cycle and making bank?

Was it fear that the previous cycle's price action would not repeat in the next cycle? Or did you make other mistakes that prevented you from making huge gains?

EDIT: Okay so a lot of the responses seem to suggest not enough starting capital which is fair enough so I'll rephrase the question. Knowing how the cycles played out, if you weren't able to at least 5-10x your investment during each bull run after your first one, what happened?