Being poor. In college in the 90s, my lead sysadmin couldn’t afford Minix for this system we had, so we tried to compile Linux on it. Three days later, we still failed, and gave up, but this was kernel 0.93 or something, so it had a ways to go. But I learned so much from that experience without paying for a university course or something.
Years later, I bought a copy of Red Hat 6 at a Costco. Windows 95/98 was big, I didn’t know how to pirate it, so I went back to Linux and it worked great on my “franken-puters” cobbled together from spare parts dumpster diving. Steep learning curve back then, though. Then I brought it to my workplace, went from UNIX admin to Linux admin, and soon I preferred it to Windows. Been my daily driver for decades, now.
Am I an evangel? A little, but I find that “right tool for right job” is a better approach. Linux is great for everything, BUT a comprehensive system like MS Office AND Active Directory simply does not exist in FOSS space yet; everything is cobbled together and a kludge still trying to catch up.
Obsessed? Kinda. I just assembled some ansible scripts to roll my own distro. Why? To see if I could.