a couple things...
-> silver bullet - if you're buying on the bid and selling on the offer, and beating someone else's price, you're actually *helping* the seller (buyer) save money. after all, if they didn't hit your bid, they'd probably be hitting the person below you...and getting less money for their shares than you're paying.
you're actually providing liquidity, as well.
-> i've completely given up explaining day trading to most people. i say that (by definition) a day trade can't be carried overnight - the minute it is, it's no longer a day trade. if they understand that, great. if not, i drop it. the press doesn't want to 'know' what it is, either.
day traders have been around since the beginning of time...just that now they don't have to be on the floor, and because many daytraders take money from the pockets of the market makers (on nasdaq), the large firms can tell their press buddies "it's all the daytrader's fault". that was the big battle cry 2 years ago, but it hasn't been sung any more...