I have pondered about this too, initially i thought the brokers were lowering the leverage to prevent high losses but on second thought i realized the brokers were doing it to protect themselves. The higher your account balance, the wider the stop loss you can set thus making you almost immune to losses, so you have an edge. I don't think the brokers like that, so they lower your leverage so that even if you win, they don't have to pay you so much profit.
