Don't feel you missed anything. I did the switch quite late into my career and being a lead/manager is a completely different job description. I felt I started at 0 and slowly got better. The learning new stuff part was fine but it is very hard to keep up your hacking skills while dealing with multiple projects/doing management things. If you are happy being an engineer, get paid well for it, and can continue to get employment as you get older, what's the issue?