As a European I am always amazed how much the US-citizen work. Very little vacation, very little security and a atmosphere of a very (very very, haha) competetive nature.
Far too much of this workaholic issue only occurs because people want lifestyles they otherwise could not afford. Two cars, the big house or exclusive location, the island vacations, and such, are not necessary for a happy life. Yet there are many who think so and adapt to make it happen. I don't begrudge them for a minute
Make sure you're not the tallest poppy...
I would call it fear. There is very little actual competitiveness in the workforce, but it looks that way as people go about trying to look important as they fear the next guy who can and will do the same job for $1/h less. The fear of taking vacation is part of this, well, for the few that get vacation time.
American priorities are messed up, work yourself to death so you can retire and enjoy life when your too useless to work.
I'm not sure there's anyone with a spine to make it change; when I've raised the issue of unionization to my co-workers I tend to get blank or vaguely fearful stares for bringing up something so untouchably controversial.
In the US, the capital is the big winner (business owner, investors, etc.) Labor loses hard -- even if you are a highly paid professional you are still going to succumb to an unsustainable culture that ruins your QOL.
And please, nobody counter this with stories about how your cool startup or tech job isn't like that. I'm talking about the majority, not various niches and exceptions to the rules.