SNIP....
From a young age I was told (repeatedly) to avoid being, "That Guy". It must have taken root because deep down inside my brain, I always tell myself, "Don't be That Guy".
I don't recall ever being told this, or any similar type of phrase in the same context.
As long as I can remember, I have been the prepped or stocked up guy. I don't ever recall a time where I wasn't prepped or stocked up on things I believe are necessary. Maybe I was influenced by my Parent's actions? My Parents would always stock up on things when they were on sale...but they never preached it. Both my parents grew up during the Depression, my Dad grew up on a farm in northwestern MN and my Mom's Dad was a auto mechanic from the late teens (that was his age, as well as, the time frame- 100 years ago), until 1977 when he passed away. That's a long time to pump gas and wrench on carburetors in the same small town, and not make much more than a good living, ie no retirement fund, just a paid off home and a paid off "one stall" business.
Anyway, back to the title of the OP, I guess my "Lessons Learned about being that guy" were not from experience, but from osmosis. But, trust me, I have learned many other things from experiences...bad choice type experiences...like the amount of alcohol a person can consume before they pass out, LOL.