Did I get old or did I just finish plucking all the low hanging fruit?

When I started on a programming journey about a decade ago everything feel exciting and I learn a lot of things per day (variable,loop,method,class,---etc)

Now a decade later I am more concern with the overall system design,algorithms usage (Big O Notation),how reliable the system it,and how the configurations are set up and how easy is it to change them.

I now notice that I don't really learn anything learn new.Everything feel the same.

Want redundancy? Use more server

Want faster performance? Make a parallel system.

Want program to run on low end device? Think about how memory and storage will be used in system.

Is this a stage everyone went through like puberty? or I am just having a mid life crisis?

PS : I haven't even reach 30 yet but I feel too old.