It's a problem with our industry. Devs want to spend time on activities that enhance their career. Because there is almost no internal career progression this means focusing on transferable skills.

Without loyalty, or at the very least aligned incentives, you will never get the most business value out of developers.

Early on in my career I was the sole dev looking after a large legacy system. For 4 years I worked really hard and added a lot of business value. I was not rewarded at all; No promotions, minimal pay increases, no respect etc. All the while my tech skills were getting out of alignment with what the industry was paying well for.