the additional nonverbal thought "Yeah, but that's not real. I could't possibly actually play with it without being scared".

Possibly. When I imagine approaching and playing with it in a controlled setting, I imagine myself being nervous, but not scared. I expect desensitization therapy would work, but only if I actually did it, not merely imagined doing it.

Do you know how to imagine it and get scared?

I can imagine, or remember, being scared, but I'm not actually scared when I imagine. (Can people normally make themselves scared by imagining things?)

you could probably pay him enough money and promise him good enough rehab later that he'll want the addiction to get the reward

Yeah, want the addiction. That yields "Aw crap, I had to inject heroin today but I spent all day on Reddit instead. Should set a timer to remind me next time.", which isn't the behavior exhibited by someone currently addicted.