Wrong on both counts.
They can cancel your insurance policy under the "Moral Hazard" clause - essentially, they are claiming that you are taking an excessive risk outside the parameters of normal behavior. "Moral Hazard" is a concept entrenched in all contract law.
As for the second part, the insurance company is betting that you will live long enough, that your premiums, and the money they make off investing your premiums, will exceed the eventual payout upon your death. All they need to win their bet, is for you to live a long and healthy life.
A life insurance policy, once issued, cannot be cancelled by the insurer except within the first 2 years, if there was misrepresentation in the application. After 2 years, a Canadian policy can only be cancelled if there was fraud in the original application. In the USA, most states do not allow cancellation for any reason after 2 years (unless the premium was not paid).
This is set out in the Insurance Act of each province. Each province uses very similar wording:
Duty to disclose
183. (1) An applicant for insurance and a person whose life is to be insured shall each disclose to the insurer in the application, on a medical examination, if any, and in any written statements or answers furnished as evidence of insurability, every fact within the person’s knowledge that is material to the insurance and is not so disclosed by the other.
Failure to disclose
(2) Subject to section 184, a failure to disclose, or a misrepresentation of, such a fact renders the contract voidable by the insurer. R.S.O. 1990, c. I.8, s. 183.
Incontestability
(2) Subject to subsection (3), where a contract has been in effect for two years during the lifetime of the person whose life is insured, a failure to disclose or a misrepresentation of a fact required to be disclosed by section 183 does not, in the absence of fraud, render the contract voidable.