between why breaks are necessary but vacations shouldn’t be?

One is literally necessary for survival while the other isn't. This is the difference between a 'need' and a 'want.'

Is increased well-being not necessary in your worldview?

Considering how many people are able to live a significantly lower quality of life than what you're advocating for, no. It's not a 'need.' It's a 'want.' There's no limit to 'increased well being.' There is a limit to what the human body can take before it can no longer go on living.

Might want to brush up on your vocabulary. This is a pretty simple concept that even 2nd graders have no problem understanding.