This ^ and it’s also a poor tax toll booth. You don’t have to pay commissions to trade on their platform which means they have zero obligation to give you best execution (in their mind), in fact they make the other half of their dough via what’s called order routing. They are paid to route your orders to whichever clearing firm has the contract. Throw in rehypothication (levered securities lending) and it’s like printing money, until of course people get buyers remorse like they are now. There’s a reason the owners started in high frequency trading.