Like said before, I think any drug has the power to turn even the straightest person crooked. As soon as the funds run low or your DOC is running out, your brain is instantly scheming a way to get the next hit/shot etc.
I'm not in the upper crowd, so I can not speak for them, but the opiate addicts I have been and dealt with are bad. Everyone I've delt with has always said, 'if you're ever sick i'll throw you something to help you". When that day comes, no one is around. An opiate user is out for themselves to the end.
Worst I have ever done is stolen money from family and stolen prescription meds from family. The latter would even work in my favor, because when said person would be short at the end of the month (from me stealing meds), he would then give me money to buy him more off the streets. I would then in turn charge an enormous inflation price (knowing he'd pay not to be sick) so I could get pills out of the deal as well. It would be a double win for me. Terrible now, but it's what I did. I've also done the thing where someone gives you money for shit and then "oops, I got robbed, or they charged 0x more so I could get shit over them.
Glad, for the most part, that part of my life is behind me.