Yes Fentanyl is a problem and does lead to a highe

Yes Fentanyl is a problem and does lead to a higher increase in overdoses because it is being mixed in lethal quantities by people who are either selling the illegal drugs or by people who think it is a good idea for a more intense high. Both groups dont know what they are doing with dosages and that is why that one is dangerous.
That said; your argument is the overly simplistic and that blame the addict viewpoint is what has driven the opioid issue to the crisis it is at. It is most definitely the fault of the pharmaceutical companies that drove the crisis and it all revolves around money/greed. Just because it was legal doesnt mean it is not immoral for them to market, distribute and drive use of a product they knew was addictive. If it were not for the pharmaceutical industry pushing opioids as the solution for every little bit of pain then it would not have got to the point where there were so many pills out there to be abused by BOTH Adults and youngsters alike.
I agree that everyone has personal responsibility for their choices, but blaming the addict is just putting your head in the sand and ignoring the dealers who market the drugs out into the population. When regular, law abiding people are told that the drug is safe and they should be taking them by an authority like their doctor, should they be totally at fault for forming an addiction??? I will reference tobacco companies as an example here. I think the vast majority of people agree that tobacco companies were the ones at fault for addictions to cigarettes which can result in cancer and other diseases...........
Humans are always going to have vices and addictions. That is who we are. But it is the job of respectable companies to know when they have an addictive product and to take the moral responsibility not to peddle a dangerous product that can easily cause users harm.