For chronic diseases that tend to be caused by obesity, the expensive bits tend to be towards retirement aged people - or are so disabling that people drop out of the workforce early.

In either case the vast majority of those costs will be incurred by either Medicare or Medicaid. Or at least the next insurer in line as the typical worker doesn’t spend an entire career at the same firm with the same insurance provider.

By the time any cost savings benefits have been realized (call it a decade later), chances are that insured patient is long gone and all they were was an additional expense.

By the time government gets involved you have someone who has been obese all their life and the damage is largely already done. Even if you paid for the meds now, the savings are limited.

Given the market already though - these drugs will be affordable to the average working person within a few years