Not a dumb question at all. Yes and no on the taxes. Yes, taxes and trade commissions both eat away at gains. Since you get to offset short term losses with short term gains, you aren't paying taxes on all the gains you make, assuming you FUBAR'd on some of the trades and took a loss. But since most daytraders don't make a ton of money, the marginal tax rate for the net gains is between 15 and 28 percent. So if you manage to trade successfully for the year, your nets will be reduced some, but not entirely by taxes. But that's better than losing money!! And short term gains can be carried forward if you weren't able to offset them in the tax year they were incurred. But they're still losses and no losses are good.
I hope this makes sense.
Market Data 
Markets 
