People tend to actually be happier in countries where there is room for improvement. People want to know that the future is bright, even when the present isn't as good. This actually makes a lot of sense, as many first-world countries that are said to have it better than everyone else tend to be the countries with all the depressed millennials.

If you know that this is as good as it gets and "it will only go downhill from here", then it's easy to think "what's the point in trying?" After all, if there is nothing good waiting for you, then you are going to be in the same position whether you work hard or not.

The "baby boomer" generation could buy a house, afford to have two or three children, go to university, and all relatively debt-free. These things that were perfectly normal fifty years ago are out of reach for most young people today.