Einstein once said "Once you stop learning, you start dying". I feel like in IT it's the case for most what people are thinking. In my case I have been switching tech because I felt I wasn't learning anything new or simply because it's was dying. I feel like these guys like him are probably too confortable in their confort zone or too lazy to learn anything new (the less you do the less you've got motivation + you can't teach old dog new tricks).