No, there's a small percentage of older folks in software engineering. In almost any other engineering discipline, you'll find many older engineers who enjoy long careers, and whose perceived value often grows with age. That's because actual engineering principles change very slowly.
Most software jobs do not involve much engineering in the traditional sense; most of the effort is keeping up with the constant churn of flavor-of-the-week libraries and frameworks, information that will be often be outdated and useless in a few years.