That's true for all industries. That 50 year-old banker is not the guy who's running around on the trading floor all day - he's probably a manager of some sort as well.
Similarly, if you go into other engineering fields (electrical, mechanical, civil, etc) nearly all the 50 year-olds are managers also.
But how does that scale? What's the ratio of managers to workers? For every 10 20-something new CS graduates, there's maybe 1 50-something manager. What happened to the other 9? This isn't a new problem, after all the Army needs only 1 Colonel for every 12-16 Lieutenants... The option to stay on as a junior officer until retirement doesn't exist, it's "up or out".
Similarly, if you go into other engineering fields (electrical, mechanical, civil, etc) nearly all the 50 year-olds are managers also.