The best reason to buy a PS3 is for its top-notch graphics.
But I'm still going to try to sell one or two on Ebay. The whole question of capitalism is an interesting one. Capitalism can be immoral. That being said, I wouldn't compare the PS3 launch to, say, scalping Rolling Stones tickets. The Rolling Stones may die next year and never come to your city again. Even if the Stones don't die next year you may only get one chance to see them in your own city unless you live somewhere like L..A. or New York. PS3s, on the other hand, will be bountiful within a year.
As for the risk, yeah, I think there's a slight risk factor in PS3 due to the high price, but looking at the Xbox 360 and PS2 launches, people seem to be willing to pay a lot more than $600 for a hot console. Is it hot, though? I don't know yet.