I used to be confused too: when spot prices drop, I can't hold, and when futures surge, I want to add more, resulting in either being forced to sell or getting liquidated.

Later, I told myself a simple truth: don't confuse "want to make money" with "can endure."
The amount of volatility you can withstand should match your position size;
for the part you can't handle, don't try to tough it out with your words.

Recently, isn't there a bunch of people watching on-chain large transfers and abnormal wallet movements as "smart money"?
Honestly, that's just information, not a talisman.
It's okay to treat it as a signal, but don't use it as a reason to bear the drawdowns.
When it comes to position sizing, in the end, it's not about prediction, but about whether you're willing to stay alive during the toughest times.

What I’ve learned isn’t skills, but this: first admit what kind of emotions make you do stupid things,
then use your position to lock that in a cage.