why do people who are too old and sick insist on working?

They can't let go of the power and attention. Their fifteen minutes isn't enough.

Different reasons for different people, but the two most common reasons I've come across are:

(1) They overspent and "need" the money. This one is complicated because I'm not saying these people are poor, actually quite the contrary, many have good careers and command a good salary...but yet somehow they lived most of their adult lives like they would live forever and didn't even think about retirement, and once they get to retirement age, they don't want to change their lifestyle.

(2) Sense of purpose and identity. This one seems very prominent in the USA, where job/career is the base of most people's identity. For many people, their career is WHO they are, and without their career, they are nothing....or at least that's the reality in their mind. I would say my Parents fall into this trap. Both my parents are now retired and they've been mildly-depressed every since retiring, even though both are financially secure and will never have to worry about money.

Loss of identity is a powerful thing.

EDIT:

Forgot to include the most obvious reason:

(3) Some people simply can't afford to stop working due to socioeconomic reasons, although I doubt this applies to Mitch McConnel.

Some folks said he may have stroked. I think he just lost his strain of thought. Mind just went blank.

Nothing else to do - no social life or interests outside of the real American religion: CAREER.

Ask Diane Feinstein or Nancy Pelosi.

they're slaves to the secret societies that prop them up. they're not allowed to retire.

If you don't know the answer to your question, give it a few years and you will. Some of the best insight was in the longest reply in this thread.

Aging, and what comes with it, truly can mess with one's sense of identity big time. And in the US, it is just getting worse. Culture-wise, America really needs to change its perspectives on aging.

Because they don’t actually “work”. Way too many career politicians and senile pantshitters in DC including the president.

People who actually work pray they can be fortunate enough to retire by 60.

These clowns jobs are easier than being on vacation.