Zero is the only number which equals its double. Your math must be wrong, because I earned a little bit more than zero since the 1970s. Actually, I only started professional programming in the late 1980s. I'm lucky my dad earned much more by selling fresh food, otherwise I wouldn't have a household right now, let alone an income.
I managed to write some good software, though. I have the feeling that adding up all the software written since the 1970s, it is a heck of a grand job we did. We may still work the same hours and drive the same cars, but computers aren't quite the same.
Possibly, money isn't just the right unit of measurement, especially since it doesn't take free software into account. Alas, we have nothing better for comparing sundry stuff. For comparing software with itself, such as 1990s operating systems vs today's ones, we ought to use evolutionary concepts. Number of individuals, total energy, entropy, anything.