I'm an self-taught old-timer. I started programming professionally in the 1970's. At the time, many colleges did not offer IT courses. I did some programming for a Numerical Methods math class and fell in love.
A freind gave me Knuth TAOCP Vol 1 and I fell in love with that. Bought all the volumes available at the time, read them more than once, and did many of the exercises.
The vast majority of my experience is on Digtial Equipment (DEC) hardware and operating systems: OS/8, RT-11, RSX, RSTS, and VMS (aka OpenVMS).
Languages: Machine code (yep - on the PDP/8), Assembler, Fortran, Basic, Cobol (dislike it), C, and a few others.
I've done a few projects on Microsoft-based systems (C and 8086 assembler on MS/DOS and Windows 3.0).
Almost all of my application experience has been for manufacturing companies. A lot of my value-added is now application-oriented - as a business consultant - how the business should best do something.
Based on Knuth, I wrote subroutine libraries for just about everything in the first three volumes. I've been using those for years.
Recently, I've been watching the MIT lecture series on YouTube. Wrote libraries for those techniques when I needed them for work.
Got heavily into the DB details/internals for databases implemented on DEC VMS.
Not much more to say, except I'm still learning and putting new learning to use.