They pre-ordered. No way that supply & demand was going to happen for someone just popping in to order a card.
Well if they did Nvidia could sue them (If Nvidia cares that is). Nvidia contractually locked everyone in to a 9/17 6am PT launch with no reorders until after the launch.
Even the scalpers had to wait till then to order their cards, however the scalpers where already able to pre-sell the cards that they haven't purchased yet with no consequence. If they get the card they ship it to their customer at a higher price on ebay turning a nice proffit. If they don't get the card they just have to give the customer a refund and Ebay won't do anything about it.
However, there were absolutely no purchase limits or Captchas and bots can move and shop a heck of a lot faster than a fleshy can.
This all reminds me of a question my son asked me ....
Son "Dad in Bayformers why didn't the Decepticons just buy Sam Witwicky's glasses off of ebay?"
Me "Captchas maybe?"