Oh shit, you're totally right. I completely forget about the initial vs maintenance. So the risk to the broker with even a 1k maintenance is nothing. If it hits the 1k bottom mark, there would need to be more than 20 ES points slippage to use up all the 1k in funds.
You are missing essential elements in your logic. As starting point you have to take your trading system. Watch the signals that are generated, and watch the stops that are used. Check how much your trading system has as open loss, so how far does the market go against your position. Check how often you get stopped out and if you don't reduce profits because of bad positioning of the stops. Watch for each big move if it moves in the right direction of your position or not. 10, 20 or bigger moves are not by definition bad. They are only bad if they go against your position. If they go in the direction of your position they are wonderful. So just saying "if the moves of 10, 20 or more points go in seconds it can wipe you out.", that is only correct if the move goes against your position. And in a good trading system these big moves go in the direction of your position, so they are a good thing.
At current price level, there is zero chance of the ES/SP opening 460 points down, thanks to circuit breakers. IB is a bad example, because they level far and above all exchange minimums upon their clients. But I think the reason IB has no day-trading margin below exchange minimums is simply because they have SO MANY CLIENTS! They have SOOOO many people trading through them, that they need that extra buffer against those who would blow out.
I was only looking at this from the perspective of the broker. The day trading margin is supposed to reflect the risk they take my letting you trade knowing that they will be responsible for any shortfall. So they look at how much can you potentially lose and when do they need to cut you off before they risk having losses themselves.
one vote for amp CQG will liquidate the account with 80% loss, so you have $500, CQG will close out you positions when you are at $100 mark. Brokers may vary perhaps higher than lower than 80% to protect their firms.
stoopid lingo I just threw out there. Typically used as hotel advertised price. But in this case in other words the published exchange margin rate. I posted the IB reduced margin rate on previous page (30% lower as opposed to many others that are 75% lower - for daytrading).
To know the risk they take (the brokers) they should know the trader. And as they cannot try to understand each trader, they just put a limit where they think they are safe. Their real risk is smaller as every big move is in favor of a part of their clients. So in every big move some of their clients win and some lose.
One of my brokers will cut off at $500 too, while another one will cut you off when I have less than 5% of the initial full margin, which is in general above the $500 level already.