[dlcarrier]

It's never cheaper for insurance to buy something for everyone. There's extra administrative costs to them being the middle man, so it makes much more sense for insurance to incentivize you to buy it yourself, through premium pricing.

For example, fire extinguishers and security cameras will reduce crime by more than their costs, but instead of charging you for them, plus administrative costs, and shipping them to you, your insurance provider will offer you a discount if you have them. (Really it's a price increase if you don't have them, but regulators don't like it when they call it that.)

Not everyone will benefit from GLP-1, so in this case, the most beneficial solution would be to charge higher premiums for anyone that could benefit from GLP-1 but doesn't use it.