A brother asked me why I use such low leverage.

I want to say that low leverage allows for longer holding periods.
The core of low leverage is trading risk for controllability, especially in the highly volatile environment of the crypto market. Preserving your principal is always the number one rule.
You can also pay more attention to those high-leverage traders—not saying it's 100% of the time, but most high-leverage traders disappear after a while. Either they get liquidated or can't handle the losses, which clouds their original trading intentions and leads them into a never-ending road of trying to break even.