Can chose to not use heroin and other drugs - like most of society had informed you - and there is infinite amount of data available to anyone looking.
The addiction initially wasn't fed by illegal opioids with a bad reputation like heroin but by prescribed medication by a trusted authority. Perhaps some people might go directly to heroin now because there's so much of it going around but the initial wave of addicts was created by companies.
Now, now. Are you implying everyone is always making decisions purely intellectually with no other inputs? People make stupid decisions for stupid reasons all the time. In fact most of the time. That doesn't make it any less of a choice.
I've been a teenager and I've known a lot of teenagers. I can totes see a teenager get into heroin for all sorts of stupid reasons. Because teenagers are idiots [1].
I prefer a society where a stupid decision at that age can be corrected for at a later time. I prefer it over a society that oversimplifies all this to 'choice', going against so much of what we've learned about human nature over the past decades.
[1]: Adults are also idiots. People are idiots. Rationality is our weapon against it, but it's so effective precisely because we're so irrational by 'default'. I'm baffled how people can still hold a worldview where 'choice' is somehow a simple concept.