As for me it was
*You never loose until you cash out*
Taught me patience.
I never liked this one. Bagholders of countless assets (from shitcoins to penny stocks) have suffered dearly for not cutting losses early enough. There should be some sort of caveat about the fundamental strength of the asset. Maybe it's okay to baghold BTC but it's definitely not okay to just baghold
anything.
There is a related (but IMO superior) adage that goes "Buy right, Sit tight." Once you've
bought right i.e. done your due diligence and bought into an asset with extremely strong fundamentals,
then you can sit tight and wait out the volatility. The idea is you can't necessarily beat market volatility, and you need to give the market time to let your fundamental analysis work.
But for example, if you've bought into a vaporware shitcoin, you haven't
bought right to begin with, and you should expect that your capital might evaporate entirely given enough time.