High leverage means you can open several trades with a small amount of money, but the problem is you will not have much spare cash left (free margin) to keep the trades open if they trades go into a loss.
So, imagine I have $3 & my leverage is 1:500, I may be able to open only one 0.01 lot size trade, but someone else who has the same $3 but whose leverage is 1:3000 will be able to open about four trades of the same 0.01 lot size.
But since my leverage is low, i will last longer in the market even if i am making a loss, i will have more time for my trade to recover into profit.
But for the other person using 1:3000 leverage, once the trade goes into loss, the broker will close his trade since he won't have any cash buffer left in his account to give his trade time to recover.