I'll just say, drugs aren't worth it if you don't have a need for them I.E. medicine.
I have battled with addiction and abused basically every drug under the sun. It took me years after getting initially sober to pull my life together, none of it was worth it in the end. I have a 3 year period of my life that I can only remember bits and pieces due to using way too many benzo's in combination with alcohol and weed, among other things...
As for the argument with weed, no it's not entirely harmless, that is just not true in the slightest. I don't smoke anymore and while I'm all for legalization of it, to believe it as harmless is bullshit. I've heard countless stoners say how it improves their lives in every aspect and that its not addicting, yet they claim they can't eat without it, they can't sleep without it, etc... umm that's called being addicted. It might not be be physically addicting like opiates, benzo's or alcohol for example, but nonetheless, still an addiction. Psychological addiction is a real thing and some are more prone to addictive behaviors than others. Take being addicted to video games for example, you're not going to die of withdrawal if you stop playing games but it is still addicting if you have that kind of personality.
All in all, moderation in everything is key. If you have an addictive personality and you're aware of it, please be careful around drugs, especially the well known addictive ones like cocaine, meth, heroin, benzos, and even alcohol, etc... you get my point.
Edit: If you're going to screw around with drugs anyways, at least check out
https://bluelight.org its a great forum dedicated to harm reduction in relationship to drug use.