Taxes are different. Taxes won't make a winning position a losing one, but commission very easily can. That is because taxes are on profit. Small profit => small tax and large profit => large tax, but that will not turn a winning position into a losing one.

In real dollars (after adjusting for inflation) taxes will most easily turn a winning position into a losing one. This has always been the problem with taxing capital, often you are just taxing inflationary gains.

As another commentor mentioned: you're not comparing against a 0% baseline, but against the relevant index fund. Or, at the very least, against normal savings accounts interest. So taxes can indeed turn a winning position into a losing one.

Tax laws for MLPs can make a losing position. Look it up!

Taxes reduce profits (and losses) but don't change a profit into a loss.

At least, not by the usual standard for "making money day trading", which ignores fixed, nondeductible costs like rent.