Learning the hard way about sizing and correlation in crypto

Been reflecting on a really costly mistake from about a year ago, primarily in the crypto space. I'd started to feel pretty confident with my trading edge on $BTC and $ETH, had some good wins, and started increasing my position sizes. The big error wasn't necessarily in the initial sizing, but in the assumption of diversification within crypto. I was running multiple longs across different altcoins, thinking I was spreading risk, but then a sharp downturn hit the whole market. Suddenly, everything I was in went south simultaneously. It wasn't overtrading or revenge trading, just a fundamental misunderstanding of correlation when the sentiment shifted hard. I watched several nicely profitable positions evaporate, and then some, because my 'diversified' portfolio all moved together. Lesson learned: real diversification isn't just different names; it's about uncorrelated assets, especially when things get choppy. My risk per trade was fine, but my overall portfolio risk was way out of whack because I ignored that key correlation factor.