Lol, at buying a massively leveraged contract and thinking you are paying 0% interest. Lol, at talking trash while providing 0 facts or understanding. Why don't you buy an ES futures contract, invest ~280K in bonds, and come out ahead of all those idiots buying SPY directly?
So you don't trade the eMini or any other futures contract yet spout off about what you don't know. Gotttttt it.
The rate spreads with the performance bond offsets (duration spreads), i.e. 2s/10s, 5s/10s and the NOB/BOB butterflies have even crazier leverage. You can put on some fucking size with that shit. (Note: I mean gross exposure here -- net exposure may actually be lower than higher margined outright trades)
You would be surprised that in almost all trades you get can get filled almost immediately by buying the bid price and selling the ask price thus saving you 2 ticks per trade. Look at it this way; how many trades do you make that you don't have at least a 1 tick drawdown? Bingo! Granted there will be some trades you will have to pay up for or just wait for the next setup.
I do it often. Even positive slippage. In this bull market I put in limit buys below current B-A. Similarly (above B-A) for sells.