Really? $10 is too much for a trade? And anyone with any reasonable amount of capital is going to choose them based on this? I don't think so. I certainly wouldn't.
And their going to make money on margin accounts and API access? Anyone sophisticated enough to be trading on margin or paying for API access has enough funds to not care about $10 trading fees. Seriously - on a $10,000 trade, that's a tenth of a percent. You've got to be a hedge fund with millisecond precision to care about that.
I'd like to be able to spend <$1k per stock, $10 is a 1% fee on a $1k order, and if you want to sell later and the stock hasn't appreciated in price another $10 = 2% total fees.
$10 each way fee can seriously eat into the EV of people looking to make small orders, and disadvantages this group against the wealthy (who already have a host of other edges!)
I'd like to spend a few hundred on several stocks, but the fee makes this not worth it. Leaves me with the option of don't, or put it all in one stock which isn't a good idea.
If they actually have lower expenses than competitors, they may be competative on margin rates. If that is true, then anyone who manages to make some money trading small amounts and wants to scale up is likely to stick around.
And their going to make money on margin accounts and API access? Anyone sophisticated enough to be trading on margin or paying for API access has enough funds to not care about $10 trading fees. Seriously - on a $10,000 trade, that's a tenth of a percent. You've got to be a hedge fund with millisecond precision to care about that.