Is it just me, or does using mind-altering substances to get through one's daily schedule seem like it crosses the line? I'm always a little baffled when people sacrifice their health for work - it's a very bad decision in the long term. You can always find another job, but once you damage your health, you may never get it back.
I think, more interestingly, I'd ask if it were to become known that modafinil (or adderall) were harmful long term, would people still use it to gain competitive advantage. If we gain a nootropic with significant effects, at what point does it become disadvantageous not to jump on the mystery train? The 'line' that can be crossed is different for everyone.