LOL oh man that sounds too familiar, my dad had sort-of the same kind of attitude until I finally gave in and started anxiety meds when I was 20 in college because I literally could not function anymore. Kept telling myself "it's all in my head" and then within a day of starting sertraline I had a revelation... "THIS is what it feels like to be "normal"!!! I still hate being dependent on meds though and hope someday I can drop them. Serious anxiety runs in my mom's family and I definitely got it bad. Heck my grandfather had it terrible and in his time it wasn't a "real thing" so he turned to drinking booze and smoking cigarettes, a LOT.
That's commendable you took the hard way and helped him by other means, a lot of parents would be too lazy and just get him on meds right off the bat and send him away for counseling.