Pain, hunger, poverty, sickness, drug addiction, extreme temperatures, loss of loved ones, loneliness, depression, lack of hope, fear, betrayal, loss of a job, loss of your home, the everyday grind of getting older with more aches and pains, slowly but surely dying, and other things that I've forgotten to mention all cause us to experience suffering temporarily until we get some relief
I agree with you in your general words of encouragement, but in the above list of ills that befall man, I think they can be separated out. For example, aches and pains, extreme temperatures, loss of loved ones, loss of job may not be the result of what the Bible calls "pleasure in unrighteousness" whereas I can see that drug addiction and betrayal are.
Jesus tell us to avoid Gehenna. It is avoidable. While you and I may have a different view of it, I think the things which cannot be avoided, like aches and pains of age can be taken on by sons of God as opportunities to mature in the faith, whereas the ills of drug addiction are brought upon those who seek refuge in drugs. One causes growth, and the other causes destruction.
The good news, from my perspective, is that repentance comes through the destruction, but it's not a route one should want to take, especially after coming into full knowledge of the truth. I would consider drug addiction to be a kind of hell on earth. I've seen enough of what it does to people which is why I see it that way, whereas the kinds of hardships that try our faith, I see as opportunities to be embraced.