Good question. Lots of factors at play with that one. Not sure it's answerable because 'harder' is subjective. But I think those saying millennials have it harder are probably millennials with no context. Just think about how many things we use during a day that weren't even around 40 or 50 years ago. Kids lose their minds if their phone runs out of juice or their microwave craps out.
I think there's far more opportunities for young people today. And when I see mentions that the economy was better...that's not true. What was different is that the middle class was supported. Doesn't mean anyone had it easier or had more 'stuff.' But when Reagan and the GOP went all-in for the wealthiest it changed the entire dynamic. And sorry, but there's not much question in my mind that there's a sense of entitlement, a demand of immediacy and a "look at me" mentality at play today that wasn't as prevalent in the past. So maybe it is harder for some millennials to have to navigate those waters. But the past also wasn't a black and white movie with a happy ending.