None of my friends who graduated with me are still software developers and I’m several years from retirement age.

There’s a bunch of filters. Many people quickly realize they don’t enjoy development, next is openings in management. One of the big ones is at ~40 you’re debt free, have a sizable nest egg, and start thinking of you really want to do this for the next 20 years?

A part of this is the job just keeps getting easier over time. Good developers like a challenge, but realize that the best code is boring. Tooling is just more robust when you’re doing exactly the same things as everyone else using it, and people can more easily debug and maintain straightforward code. So a project that might seem crazy difficult at 30 starts to just feel like a slog through well worn ground.

Having significant experience in something also becomes a trap as you get rewarded for staying in that bubble until eventually the industry moves on to something else.

I recently hit thirty years of professional software development, in companies large small, profit and non profit, proprietary and FOSS, I have led teams of forty, sat in a corner as the only developer and one thing I know in my bones - I love making software and money just means I get to code what I want instead of what The Man wants.

In fact I already have my retirement planned - a small near flat in Argostolli, a walk down to the coffee bars on the harbour and a few hours adding code and documentation to a foss project of my choice before heading to the beach with grandkids.

Now affording retirement might be interesting but not having coding in it will be like not having reading and writing

You're probably from a privileged environment such as working in the US (probably in a top location) and probably from a top university or you were there at the right time to join a top company as it grew rapidly.

The first paragraph probably applies to 1-10% of developers worldwide...