There are good and bad employees in every age group, but to get to retirement age, you had to survive a lot BS, misery, and layoffs over the years. Not everyone could take it or make it. These are the survivors.
Millennials bring some unique and valuable skills, but when it comes to all of the experience and knowledge needed to manage multi-billion dollar projects all around the world, there will soon come a day when these old geezers are sorely missed. You just can't replace hard earned experience with bravado and the attitude of "we can do it all, get rid of those old guys".
Even if an old geezer appears to be just sitting in his office all day, which some do, you might be surprised how often his phone rings or someone stops by asking for help with a problem they have never seen and don't know how to solve. And you won't find those answers in books or on the internet. The money they can save the company far far outweighs their salaries.
When I need a contractor onsite, I am always glad to see some gray hair.
How many of you think your parents and grandparents are worthless old fools because they are at or past retirement age? Want them treated at work like they too are worthless? Every hear people say that the older they get, the smarter my parents were?
Have some respect for your elders, even if you don't see them earning it. You have to make it a long time to walk in their shoes and chances are that most of you have no idea what an asset many of them are.