Maybe op has to throw more light on what he meant as I am also trying to comprehend what he mean over there. Of course 25x seems to be too higher for some who doesn't have much equity and could be liquidated then just imagine 500x how do you think he could survive the market if things happens to go the opposite?
You guys are not understanding OP.
He is saying that he is using a broker that offer him 20x of his deposit which 20:1, anything he deposit is allow to borrow 20 times of that amount but he want to close the account. He is looking for account that can give him 500x power borrowing power, so that anything he deposit can allow him borrow upto 500x.
What I don't understand about OP is why the sudden switch to 500x, that's over 500x leverage that can have him liquidated on a blink of an eye, this is more than gambling.