Now if I give some more money the product suddenly gets a longer expected minimum life ?
Errrrrrrrrr, yes.

Most stuff that fails does it in the first 72 hours, which is within the manufacturer's warranty period. After that you can just think of it as taking out an insurance policy. Life insurance, house insurance, automobile insurance etc.

You will also find that most retailers do not take the bulk of the risk themselves, they re-insure with a regular insurance company, so effectively, a good proportion of what they earn is in brokerage/agents fees rather than underwriting the risk.