I took this from the Huffington Post link I provided. I chose a "leftish" site just so you would not think I was cherry-picking. It presents
exactly the position I have been arguing for.

eace
Why are we doing all of this anyway again?
The theory behind the individual mandate is that the way to create an insurance market that lets people with pre-existing conditions get covered at reasonable prices is to
make everyone participate.
Without some way to push healthy people into the insurance market, the fear is that it'll fall apart. Mostly sick people would get insurance, which would drive up prices, which would lead to healthier people deciding not to buy any, which would force insurers to raise rates to cover their expenses, which would lead to even more healthy people opting out.
That cycle is called a "death spiral" in insurancespeak.
The individual mandate is not a popular policy at all for obvious reasons (Obama himself even
used to oppose it). But the Supreme Court ruled two years ago that
it's Constitutional, so we have to deal with it. Massachusetts has had an individual mandate since 2007, and
it's worked out pretty well there.