I also don't agree entirely that leverage helps. It just increases your return, and your vol. Data fees and other expenses aren't that high. So most of your costs aren't fixed costs; they'll scale with size. If your return is negative after commissions leverage will just make it more negative. However if you can do better than breakeven then of course leverage can give you a decent return; at the cost of more risk.
It's for that reason I prefer to work out costs in sharpe ratio units. Actually the cost of SPY isn't as bad as you say - its one of the cheapest things we can trade (due to a combination of high price, tight spreads and high vol).
Commission on 200 shares with IB is $1, or $2 per round trip
I'd say slippage is about 0.02 per share (bid ask is 0.01), on 200 shares $4
So on 200 share blocks we're talking $6 a trade.
Vol is about $32 a year, or $6,400 per block.
Costs then are $6 / $6400 = 0.0009375 SR units.
Doing 250 round trips a year comes in at 0.23 Sharpe Ratio.
In comparision the NASDAQ future costs around 0.18, and this is one of the cheapest futures I know. If we can't make day trading work on these two things we can't make them work at all.
What proportion of your account that is; well if you were unleveraged and buying $200 x 200 shares each time you'd have a $40,000 account and it would be costing you $6 x 250 = $1,500 = 3.8%. Data costs might be what $120 a year? Lets keep them out of it to keep things simple.
If we double our leverage and buy 400 shares with $40000 costs exactly double (at this level of trading fixed costs aren't a problem) to $8 a block, or 7.6% a year. There might also be another 1% or so to pay in margin costs.
Alternatively if we halve our account size and keep the same to double leverage again it will still be 7.6% a year, or maybe 8.6% a year with margin (though fixed costs will go up slightly).
The point is with no leverage or double leverage if you can't make 0.23 SR then you'll lose money. If you make 0.20 SR then you'll make pre costs 3.2% a year unleveraged, which means you'll lose 0.6% a year. If you double the leverage you'll make 6.4% a year unleveraged, and lose 1.2% a year, or maybe 2.2% a year with the margin on top.
Now making 0.23 SR on one instrument is I think reasonably easy. I reckon I can make 0.40 SR for example. However I'm personally uncomfortable with giving up more than half my return in costs; receiving a net small sharpe ratio, and having to borrow big to make okay money. Unleveraged I'd only make 2.7% a year; to get to my current expected average return of 18% a year I'd need to leverage like eight times - far too much. Since with the stuff I trade I can get 0.40 SR trading daily, or once a month, there is no benefit to day trading. Instead I expect to pay about 0.05 SR a year in costs.
But suppose we can make SR 0.80 or 12.8% a year gross. Then unleveraged we'll earn 9.6% a year after costs. With double leverage we'll make close to 20% (I wouldn't personally pump it up any more than that).
If you can make 0.8 SR pre cost and 0.57 post day trading, then these costs are pretty decent. This doesn't seem improbable (I've seen figures on this site implying sharpe ratios of 13..... which is a bit harder to swallow).
Of course the problem is it doesn't seem that many people can make SR 1.0 day trading one instrument, or perhaps they are all just trying to do it with more expensive stuff.
The article referenced is written by a vendor with an agenda to sell the fake dream.
Its not impossible to be profitable. And its not easy. Its just very very very hard to overcome very very very high expenses.
Lets say you only trade SPY (price around 200 currently).
You only put ONE trade a day (RT). This is about as low frequency as you can get as a daytrader.
It costs you about .01/share to enter and exit a trade using a low cost broker.
So that's .02/share RT.
So your commission cost at year end is .02*250 = $5.
Now 5/200 = 2.5% loss every year just due to commissions.
Now add slippage, data fees, all other trading related expenses.
You can easily expect expenses to eat up at least 5% of your account each year WITHOUT even having any losses.
That is a HUGE and constant headwind even for this very LOW Frequency trading system.
The more you trade the larger the expenses drag your account into the red.
Over 90% lose only due to expenses period.
The only way to increase your chances is to trade as infrequently as possible, wait for the fat pitch, and be a pig when everything lines up. But all daytraders do the complete OPPOSITE of this.
I just wasted my time typing this as very few trade to win.
Everyone knows the statistics backed up by thousands of studies but they just deny the science.
Most just trade for excitement or to act out some impossible fantasy.