If you're from the average middle class, your risk taking abilities start going down after you have a family and responsibilities coming in over a period of time. You're by then used to your workplace and a master in handling the politics and number games at ease because you know the internal dynamics pretty well. If you had joined a company in its early stages then you're probably sitting on a huge equity as well, along with the organisation paying you a good salary.
I've seen many people moving out from an organisation after spending 10+ years and then coming back to the same place just because they didn't like their new job/place. As people age they don't wanna take up new BS and drama from elsewhere.
Early in your career you seek aggressive growth switching jobs. But over a period of time we all saturate. Few folks feel saturated very early in their life too. Sustainable growth is heavily underrated these days.