No, that's not how insurance works, but it's how they want it to work. Usually when you get insurance through e.g. work, you get put into a pool that averages the costs and risks across the pool. That makes it's more affordable and is why "insurance for a single person" e.g. for sole practitioners is not a thing.

Also, usually when insurance companies flag you for things like pre-existing conditions they don't just make it more expensive, they just deny it. Or if they do allow it it's so expensive so that it doesn't make sense to buy.

In other words, if insurance worked the way you think it should, there would be no point to it at all, you may as well just pay your costs out of pocket. Personally, I think that idea is 3rd world country level shit. Health care should not be for profit.