Jesus H. Christ on a gluten-free cracker. Millennials are having problems because the workplace is DIFFERENT now.
Training? Oh gee, if you want competent workers, you have two choices: teach them in school or teach them at work. Employers have killed schools and killed unions and now they are whinging because people don't know the job. And they won't hire older experienced ones. STFU.
Work ethic? Millennials work the minimum for survival, just like slaves. Because any more than that enriches someone else, not them, and they damn well know it. They have no job security, and thus no company loyalty, nor should they. Gone are the days when a job bought you a decent living, respect, good health care, a benefits package, and a respectable retirement. Now it takes 2-5 jobs per household just to put the beans on the table. That's a disgrace.
Happiness? Older people trashed the planet and trashed society and trashed the economy -- several times! -- and then are surprised when younger people are unhappy. Surprised when younger people hunt around trying desperately to find something that will generate enough energy for them to keep going. Hey assholes, you better hope they find it somewhere, because these are the people who will be wiping your decrepit ass when you're too old to do it yourself. You better hope they're not all dead of depression or climate change by then. Or too PTSD to care if you die on the floor.
You know what, employers? You don't get what you don't fucking pay for. Go die in a fire and stop blaming the victims.