I will never understand why anyone would start doing meth. Most drugs have a few actual satisfied customers. For example, I tried coke once. I'm not going to do it again, but it was a fun experience for the most part and I'm glad that I gave it a try.
I have never heard anyone say the same about meth or heroin. I've never known anyone who just smoked meth on the weekends and lived an otherwise normal life.
The first time you drink alcohol, smoke pot, do coke, etc, you can tell yourself "sure there are degenerate alcoholics, lazy pot heads, and coke fiends out there, but I probably won't end up like that." With meth, you take the first puff knowing that you're giving your life to the drug. The difference betwee coke and meth is like the difference between driving too fast and intentionally driving into a tree at high speed. The former is risky behavior. The latter is gauranteed to kill you or horribly screw up your life.