This article repeats the idea that the tenure of SWEs at large tech companies is only 1-2 years, but I don't think this is true, and certainly not at the lower bound of one year. I am not sure about other companies but at Google, where I work, the average tenure of a SWE is over 5 years.
At least for the US (and I suspect for most other countries), that is incorrect. When adjusted for inflation both median wealth and median wages have increased in the last 30 years.