I think Hopper would be the only one worse off though?
Really ?
I think Jonathan would be worse off, he was a complete friendless outcast in the beginning
Will- he doesn't mature at the same speed as his friends, he still wants to be playing D&D when his friends mature (not saying D&D is only for kids, but part of the plot) if they didn't have a shared trauma I'm not sure the friendship would have survived.
Lucas- he joined the jocks, without the upside down he would have left his friends in the past.
Nancy, seems set to replicate her parents, thinks it is edge to date the bad boy - would get pregnant/settle down instead of following her dream and reporting.
Steve - vacuous, following his parents plan. He is better because of what happens
Robin- still awkward, not having a friend she could confide in, or friends.
Eddie, still stuck in highschool, no purpose or future.
Max- controlled by her racist step brother, living in an abusive family - we see how he treats Billy.
Billy - abused by his parent
More I think about it, the less I like the time travel change history option.