This is a really difficult question. I suppose that theoretically you are correct since insurance is just betting on how healthy a person will be in order to make money from insurance payments from healthy people and minimize the losses from sick ones. There are two problems though. First it would all have to be policed. The health insurance people would have to send out agents to check how healthy you are eating, give you urine tests and to check how fast you drive, or whether or not you choose to dive from the 12 ft diving board of the 3 ft. board. The second problem would be to decide exactly what is healthy for everyone. Some might say eating one quarterpounder a year is tolerable, but others might say it's okay to have two a month. And then, how much sugar can one put in one's coffee? Is this amount different for diabetics? Is it unhealthy to drive a convertible, even if one's driving record is flawless? Is it unhealthy to play football, even touch is a little rough. Would people who have desk jobs have to pay more since their eyesight seems to get bad from staring at computer screens, and they get headaches, and sometimes back problems?
Do you see what I mean? If it were possible to magically know if everyone is doing his or her utmost to be healthy, then it would be a good idea to charge those who are certainly livining an unhealthy lifestyle more, but it just isn't feasible.