If you'd set up several GPUs right at the start of a difficulty adjustment period, you would have had two weeks in which you drastically sped up the production of blocks. Not only would you mine most of the blocks but you'd mine a shitload of them. Then you could get millions every 30 minutes.
If you were really evil as well, you could even ask two people if they'd buy you a pizza for your coins, then receive both pizzas and double spend using your >51% hashrate. Then you could have stolen a whole pizza on top of that!
And I always laughed at my teachers thinking computers would do all the worthwhile math for me.
Math Teachers 1 - Gamers 0