That would make sense if you were doing something like buying a lifetime cryonics subscription upfront that could not be refunded even in part. But it doesn't make sense with actual insurance, where you stop buying it if is no longer useful, so costs are matched to benefits.

• Life insurance, and cryonics membership fees, are paid on an annual basis
• The price of life insurance is set largely based on your annual risk of death: if your risk of death is low (young, healthy, etc) then the cost of coverage will be low; if your risk of death is high the cost will be high
• You can terminate both the life insurance and the cryonics membership whenever you choose, ending coverage
• If you die in a year before 'immortality' becomes available, then it does not help you

So, in your scenario:

• You have a 10% chance of dying before 40 years have passed
• During the first 40 years you pay on the order of 10% of the cost of lifetime cryonics coverage (higher because there is some frontloading, e.g. membership fees not being scaled to mortality risk)
• After 40 years 'immortality' becomes available, so you cancel your cryonics membership and insurance after only paying for life insurance priced for a 10% risk of death
• In this world the potential benefits are cut by a factor of 10, but so are the costs (roughly); so the cost-benefit ratio does not change by a factor of 10