The laziness is an illusion of human reaction.
If generation Y was truly lazy, than that would mean that there would be an obvious decline in the employment of unskilled workers that is unrelated to the current situation of the economy, and what we actually see is that the employment of workers is inline with the economic situation.
Secondly, why many people seem to believe that the "Yuppies" are lazy is that we, as humans, pay more attention to negative things, than positive ones. You notice, and therefore remember the fact that teenagers are sitting on their butts, playing video games, but when they do productive things, like getting jobs, and doing homework, you ignore that behavior as normal and therefore expected. This causes an imbalance in the perceived view of the individual.