"4 years in" I am not sure what "in" means, but I started getting paid for programming in 1984. So, what do I wish I knew in 1988? I think you already said it

"4 years in" I am not sure what "in" means, but I started getting paid for programming in 1984. So, what do I wish I knew in 1988? I think you already said it: "I'm also realizing there's SO much more to learn." Don't stop learning. It was probably around 1988 when someone suggested I look into Lisp and I dismissed the comment at the time, although I did look into AI. I do wish I had known more about Lisp, not necessarily programming in Lisp, but just the knowledge of the concepts that come out of learning Lisp: garbage collection, stacks, lists, trees, macros (not the terrible C macros I was using at the time but Lisp macros), parsing, code generation, profiling, the benefit of programming in a more functional way, and I am probably missing a lot of things here I take for granted. Don't stop learning.