Haha, well, I can only assure you that it's basically just fine. Nobody gets hurt. It's just a thing people do - like drinking coffee or energy drinks. But it works better.

In the case of amphetamine-related stimulants (ritalin, adderall, dexedrine, speed), it's easy to come off them if you aren't abusing them for pleasure as opposed to work. There's a level of use that enables effective work, and then another much higher level that makes you feel 'high' all the time. If you get high every day, you might well get addicted. But I've never seen it - I even abused my ritalin pretty heavily for pleasure for months and then stopped cold turkey (by accident), and it was just fine. I was mentally the same as I was before the ritalin, and no side effects that suggested physical addiction. I wouldn't recommend it though, it might affect different people differently.