How on earth does whole life insurance generate profits?

So - a whole life insurance policy offers a 100k death benefit for a 1k yearly premium. The policy matures when an insured reaches the age of 100, thereby rewarding them with a check for 100k plus interest. An insured accepts the policy at the age of 30, meaning that there is no possible reality where they pay more than 70k. I understand that insurance companies tend to invest their available money into bonds, often gain money from insureds upon early policy closures, and have processes much less simple than the one I described, but this system still makes no sense to me. The concept of whole life insurance doesn't add up in my head. Am I missing something? Is there more to this that I don't know about? How could this process possibly generate a profit, let alone keep a company alive?