You just answered your own question.
If the parts didn't wear out, break etc then you would not buy any more.
A company only can survive if it has cash flow, i.e. you have to buy replacements for what ever it is that they sold to you in the first place.
Second if they did make a product that lasted for years it would be very expensive. That is why LEDs are so expensive, the manufacturers know that they will last you much longer than incandescent lights.
From a consumers point of view it would be nice if it lasted longer but that will never happen.
