Bitcoin psychology

Hi everyone, I’ve been investing in Bitcoin for a few years now, and I'm already used to the roller coaster ride - but only in small amounts.

I’m firmly convinced that now is the right time to invest a significant amount of money for the long term, provided you can hold onto it for a long time. But a little voice in the back of my head keeps telling me, “That’s unreasonable,” “That’s not enough diversification,” “Bitcoin could keep falling indefinitely,” and so on. Do you guys know what I mean?

I’d bet that Bitcoin will be higher in the next 5–10 years than it is now. It would be silly not to jump in now, if you can afford it. So my question is: how do you calm that voice? Any experience?