It's wishful thinking to expect that all people are capable of full responsibility for their actions and deserve the ill consequences of their choices given unrestricted access to everything. Our free will, motivation, goals and core values can be chemically altered - probably even more so in future. There's a tradeoff, there's an optimal amount of restrictions which results in best outcomes for most people, and while I'm not certain where exactly that optimum lies, I'm absolutely certain that zero restrictions is not that optimum.
Yes, heroin alters your free will. That's why it shouldn't be illegal. You should not punish someone dealing drugs to support their non-free will'd habit because the drug removed their intent.
Also all of the examples of destructive heroin addicts you know are from a system that prohibits it. You don't know what our culture would look like in a free market drugs universe. Knowing that there is no safety net, you would probably get mocked and beaten up for expressing an intent to use heroin. Addiction wouldn't be externalized to the government, and families would have to deal with addicts instead of the prison system. Culture would evolve drastically. People have coexisted with addictive plants for thousands of years before the police state showed up.
the important question to ask is how much of this is inherent to the drug itself and how much is a consequence of prohibition. my take is that most of the horrible things that heroin addicts do is a result of the financial/legal situation that prohibition puts them in, not the inherent effects of the drug. in my experience, opiate addicts with a secure supply tend to be docile, if unproductive, members of society. I wouldn't say the same for alcoholics...
It would become a lot more efficient without prohibition. A lot of heroin is derived from laborious manual processing of opium from poppies.
The agricultural-industrial complex would plant a field of a potent strain, fertilize it, let it grow, chop it all down, crush it up, extract out the goods and probably 5x+ crop yields with a team of 2 or 3 operating thousands of acres.
That's not happening in Myanmar or Afghanistan!
Morphine/heroin would be a dirt cheap commodity without government prohibition. Morphine is a natural product. It is harvested and extracted industrially not unlike stevia, cacao, or coffee. There is nothing uniquely capital-intensive about the process except the smuggling.
Murdering cartels and private prison owners became billionaires off of enormous human suffering because someone wrote a law.