There is a slippery slope here: If taking moderately effective drugs with no side effects becomes commonplace, there will be pressure to take more effective drugs with slight side effects, then possibly very effective drugs with considerable side effects. Just like in sports.
In my opinion, this is not something to be afraid of, but something to be aware of, and debated.
However, there is a very real downside: lack of sleep. I know one guy who went off the fucking deep end with paranoia and deceit after taking this stuff for around a year, non stop. He slept, but not much. From what I can tell of my friends who take these drugs, they're great for the occasional week of crunch, or 48-hour coding binge, but as a daily thing, be very careful to stop and rest your body from the stuff after a week or month.
The way I see it, jobs that can be done better while doped will have pressure on their executors to continue to supplement or lose the position.
That's not to say it's hopeless, just that highly competitive jobs might be out of reach for those of us who decide that they don't want to be drugged.
I look at it like professional sports. So many athletes use performance enhancing drugs, that to compete with the pros, you need to take them as well.