Personal computers clearly illustrate this statement. Anyone who wants to replace a three to five year old computer finds that the trade-in value of their computer is almost nil. On the bright side, one finds that the complexity and performance of the current systems vastly exceeds that of their old computer and that for about the same purchase price, adjusted for inflation.
While this economic reality reflects the massive growth of the industry, it is hard to even imagine a similar growth for instance in the automobile industry. No one would even expect a five times faster car with a five times larger capacity at the same price of a five year old vehicle. But, when it comes to personal computers, such expectations are very realistic.
The key fact which has driven the successful growth of the computer industry is that through industrial skill and technological advances one manages to make smaller and smaller transistors. These devices deliver year after year better performance while consuming less power and because of their smaller size they can also be manufactured at a lower cost per device.