I did qualify #1 with "obviously not true for everyone, but could account for something". And I speak from some experience too. I'm 34 and have lived through the platform I was invested in disappearing almost over night and having to quickly get up to speed on some new platforms and languages over the course of about 6 months while I supported myself. It was quite exciting, but also quite stressful and tiring. If I was faced with the same event again I think I might opt for defaulting to a more managerial position rather than try to become expert in a new area again. Everyone's different of course, but I didn't make the point lightly or naively.