After two and a half years of frowned upon enterprise, thousands of needles, and 300-400 thousand dollars, cash, wasted.
Wait, no, wouldn't earlier be better? I have good stories to tell, but that doesn't outweigh the sheer loss of it all. Some drugs you cannot use appropriately, no matter what you think you "know", having apparently completely forgotten Socrates' lessons....
That hasn't stopped me, but that lesson of Socrates' has become very poignant to me, at least. Know that you "know" nothing, and your best idea is a guess. Apply that to your drug use, and take the appropriate care in light of your awareness, then you still won't know when to stop. IME, some drugs make it so you only stop if your environment pretty much forces your hand.
Sucks, but at least I know I'm human and therefore an animal; subject to many cognitive flaws and more unjustified confidence than we should rightly have.
If I sound a little cynical, it's probably for a good reason. I could have my doctorate now, plus nearly a half million dollars. I have neither, little hope for the latter, and quite some time before the former becomes reality. All because I couldn't/wouldn't stop, and worse, to my deep shame, thought I was in control; thought that my knowledge gave me an edge, made me know "how" to use a substance. You're fooling yourself if you think you have much power against your own neurochemistry.
I've used since quitting, and managed to know when was enough, understood limits. But I've had to deal with addiction, then dependence, then quitting opiates and stims on my own (fuck rehab), in order to get to this point of experiental understanding, not to mention reams of research time likely better spent elsewhere.
Just know that you are flawed, and can't be trusted much more than lab rats shooting coke over food, or smoking orangutans in zoos, or any other mammal granted the boon of power over it's own neurochemistry. It tends to end badly. If you believe that, you do have a small edge; you know never to fully or even midway trust yourself. With such uncertainty a part of your consciousness, at the very least you'll take that exta bit of care.
Using drugs isn't a game, or a joke, or even a competition. Drugs are tools, tools can be used detrimentally or amelioratively, the same is true for drugs. But like some tools, such as nuclear weaponry, propaganda, or even projectile weaponry of any type, drugs are often either misused, or used to much. The only difference is that we fuck up the environment, societies, and individuals with the those tools, drug-tools enable us to achieve the rarer ability to fuck up your own brain; your mind, your thinking, your logical ability, your memory, and your own emotions.
Used right, any tool is good. I question whether even 3-5% of the general populace has sufficient self-knowledge, experiential awareness, and strict conformance to preset planning/logic/decisions, to adequately actively engage in the pursuit of altered neurochemistry/consciousness. Not that it will stop anyone: the very premise of my beliefs in this regard predict that only a distinctly small portion of humanity have the ability to use even a well-developed and logical warning of the potentialities and intrinsic properties of psychotropic chems. I know I never listened to the ones offered to me; though I thought I was well aware and able to control it all. Why should you, or anyone else?
I only offer the experiences and knowledge of someone who has walked the paths for years, someone who knows this stuff better than his own mind. A humble cautionary entreaty, offered from someone with cause to offer it, earnestly and sincerely given. Do what thou wilt, but at least take these two maxims to heart: question authority (especially your own), and know thyself.