Yeah seems pretty arbitrary. $300 is the average monthly salary in Sri Lanka, that would be a lot of money there. It’s 10X the monthly salary in Afghanistan so that would be a shitton to keep in a custodial wallet for them!

Treat it like cash in your wallet - don’t carry more than you’re willing to lose the same as you wouldn’t carry more cash than you’re willing to lose. Much easier rule of thumb and scales to everyone per their own individual wealth and preferences.