Most importantly, how to reach agreement with different stakeholders on decisions where you have insufficient data. That‘s where making an argument comes in. You weigh different alternatives. You show the consequences. You conduct workshops - where in the end the people might have gone through the same thinking process you have gone through, but now they are buying in to the idea. You learn to manage up and across.
You learn when to step back. Where you should let others shine and enable them making a career. And become a mentor.
You learn how to take risks. That you need to balance high-risk, high-reward projects with quick, short term wins. That you need to find out how to do both at the same time. One securing the funding for the other.
You learn that relationship power always trumps knowledge power and power through authority. You learn to get to know people as human beings and learn about their motivations.
You become a servant of the team, filling in the gaps where they exist. Because you can.
I‘m still writing code as well, as I have since I was in my teens. Still loving it. Writing a piece of code that solves a difficult problem in a beautiful way makes me high.
I feel a lot of people move to dev management when they get older or just find a spot where they feel comfortable and the pay is good.
It isnt that hard to stay "current"; while espousing working technology over trendy tech.
I find much else, it's about data at the end of the day - getting good at modelling processes and flows will never hurt.
Take a mentor stance: I might not be hands on the tools, but I'll train the next 10 developers - its a provable way to actually make yourself 10x as productive if you tell them not to repeat mistakes you made and provide vision. Hack on things occasionally. If junior devs smile at your ways as quaint, spend the time to find out why, upskill, then apply experience to whatever flavour of the month exists.
I love the fact my my career is older than most of my coworkers, it doesn’t make a whit of difference except I know a lot of useful stuff. And I don’t work for a big public company. Come to think of it, my last 3 VC funded startups were great for all ages as long as you had talent.
Consultancy, doing T-shape tasks on projects, jungling between Java, .NET, native and Web, using other languages when required to do so, taking over DevOps related tasks when needed, architecture and sales support.
"Jack of all trades, master of none", whatever makes the customer happy at the end of the day.