Competition between insurance companies will create lower costs for those with pre-existing conditions?
Why do you say that competition between insurance companies will create lower costs for those with pre-existing conditions? No one else has said that, but you. You seem to have a very warped view of what insurance companies are for.
Insurance is a gambling game where you bet on what will happen
in the future. You "bet" that you will get sick or injured, and the company "bets" that you won't. If you get sick or injured, the company pays you the stipulated amount (paying for a portion of your medical treatment etc.), and if you don't, you pay them (premiums). The purpose is to shield you from the "shock" of suddenly and unexpectedly getting hit with huge medical bills... which is why you agreed to the contract.
A pre-existing condition cannot be insured against. It's like betting on the outcome of a horse race that's already been run - there is no "chance" involved, and no "unexpectedness" to the outcome (any more).
Insurance companies are in the business of selling security - the assurance that you won't be suddenly bankrupted by huge medical bills, rehab bills etc.
in the future. They do it by insuring huge numbers of people and getting them to each pay relatively small amounts (their premiums) each. They and their clients all know that most of them will never incur the huge medical bills they are worried about. But since no one knows which few people WILL incur them, they are all happy to pay the premiums, for the knowledge they won't have to pay the huge amounts if they turn out to be the unlucky ones.
Insurance companies sell safety from FUTURE possible disasters. And that's all they sell. Asking them to cover pre-existing conditions, is like asking a submarine designed to design a supersonic jet - it's got nothing to do with his business or his area of expertise, and he never volunteered to design jets in the first place, for good reason.
If you want to set up some kind of universal pool to pay for pre-existing conditions, fine, go ahead. But why drag insurance companies into it? It's got nothing to do with their areas of expertise, and they never volunteered to do it in the first place - for good reason.