Do we get high on "methampetamine" naturally?
All the drugs I know of are closely related to a molecule we produce naturally or are a molecule that gets produced by our body. This is kind of the point of drugs. But the main issue is the dose. We all have uranium in our bodies, does that mean consuming it isn't bad for you? Or to put it differently: We all have bones, don't we? But putting another bone into your body isn't really considered healthy. 

First of all: Chemically, those two molecules of course are not the same. Let's get the obvious out of the way.

I think this is the wrong forum again because really what you are asking is more of a legal/ethical question than a scientific one (both questions). But I'll try to answer the 2nd question "scientifically" with a light esoteric touch: Consuming drugs means messing with a delicate balance in our brains that is so complicated we do not even begin to understand it. I'm not saying don't use drugs, I'm just saying maybe you want it to be not as bad as it really is.