Most people don’t change jobs or insurance companies every few years. When they do, it’s often within similar regions and industries so the chances of ending up right back under the same insurance company are significant.
Regardless, the issue is more complicated than your line of thinking. Insurance companies have very small profit margins. Current GLP-1 drugs are expensive, around $1,000 per month.
So each patient on GLP-1 drugs costs an extra $12K per year (roughly) or $120K per decade. That would have to offset a lot of other expenditures to break even from a pure cost perspective, which isn’t supported by the math. So the only alternative would be to raise everyone’s rates.
I know the insurance industry is the favorite target for explaining everything people dislike about healthcare right now, but at the end of the day they can’t conjure money out of nothing to cover everything at any cost demanded by drug makers. These drugs are super expensive and honestly it’s kind of amazing that so many people are getting them covered at all.