@glaroc the half-life for Adderall is 10 hours. The way half-life works, is that it takes generally 4 half-lives for a substance to be cleared from your system. That would be around 40 hours for Adderall.
Also, the "high" is just that it makes people feel a way that they like. Anything could give you a "high". You just don't associate that word in the same way, but it really is how it works. People wouldn't be so addicted to certain substances, I'm sure, if it didn't make them feel good. Adderall can lead to addiction and eventual abuse from those that don't need it.