Breaking down some possible factors:

1. Rich people spending their way to better health by purchasing healthcare services

2. Rich people spending their way to better health by purchasing healthy food, gym memberships, and expensive healthy habits

3. Rich people having higher conscientiousness, and this pushing them toward healthier habits regardless of expense.

4. The same genetic makeup that makes you rich also makes you healthy.

5. Being healthy throughout your life allows you to become wealthy more easily, by letting you work harder with less fatigue.

My estimation is that your healthy years come before lots of lifestyle interventions (drugs,surgeries, etc)- they are the years that your healthcare consumption is more or less moot. So I think factors 2,3, and 5 dominate here.

Better healthcare when you are young gives you more healthy years. That's why the fields of pediatrics and non-geriatrics exist. Losing your teeth, eyes, muscles, etc has knock on effects.

Rich people live in nicer areas and are exposed to less pollution.

Another possible factor: rich people experience less chronic stress, resulting in lower risk factors for various diseases.

Here’s another: being sick makes it harder to create wealth

I had always wondered if the catch phrase "eat the rich" was meant literally. Thanks!