I know what lesson you're talking about. I've been taught that lesson many times. I hope you're smarter than me, I can't seem to learn from these lessons - I always go back.
I've had extremely negative drug events. Once I decided to drink an entire bottle of Robotussin to get high (the drug is called DXM. I ingested 800mg of it.) I experienced 18 hours of hell. But even though I went through hell, I experienced moments of absolute bliss. It's hard to explain. DXM is a very extreme drug. While you're on it, it takes you to other dimensions literally. Every time I'd close my eyes, I'd instantly go into another dimension. I'd forget who I was, and where I was, and I'd only exist in this other dimension for what felt like infinity. And then I'd open my eyes, and I'd snap back in to reality. It was hell, because I was scared. I wasn't ready to experience infinity. But when I'd close my eyes, it took me to dimensions that were heavenly. SO I experienced heaven and hell that night.
I guess what I'm trying to say, is that hard drugs are kind of a bad thing, and they're kind of a good thing, too. Hard drugs can be fun, but they are destructive. Hard drugs can give you insight - but sometimes they can give you insights into things you shouldn't know. Sometimes ignorance is bliss.
If you normally have anxiety when sober, stimulants are always only going to make your anxiety worse. Stimulants aren't for people with anxiety. Stimulants can give you the illusion that you're being productive - but you're not. The only thing stimulants are good for is 12 hour masturbation marathons, picking up every speck of dust off your carpet, and looking out your curtains waiting for "them" to come. I look back at myself when I was tweaking, and I laugh my ass off at the outlandish shit I did. You're gonna think back on this shit and laugh at yourself dude, I swear to god.
Marijuana is safe. Weed will never let you down. Weed is a provider - it will give you everything you need, you don't need any other drug. If I could send a message to myself in the past, it would be "don't do any other drugs except marijuana." Pot heads are cool, calm, and collected. Weed will make you mellow, and provide all the happiness you need.