I worked my bum off for 10 years. Saw that it had no effect on my career prospects and then gave up. Wiser employees gave up way before then. I've not seen a single promotion out of development in nearly 20 years in the industry. It's a simple fact at least in the UK, that one does not progress out of software development. Senior/lead developer is easy but after that there is no progression. Development manager roles are hard to come by and require growing into the role. Moving sideways into project manager or scrum master roles is generally very difficult to engineer as well. The simple fact is that engineers are seen as line workers. Line workers are not managers and are not suited to the role.