Most RR folks who were also "fans" were among the best and safest folks, I've worked with... A lot of folks are closet fans, as you note from former rails on AP, it's a job that takes a lot of commitment, and it probably doesn't hurt, if you like trains.

However, I had one "foamer" as a fireman (and he was a promoted engineer), who my crew didn't want me to allow to run the engine.

He was always distracted by his "foaming".

And worse, he never got the "feel" for how to handle a cut or train, he always stopped "short" (too much air), or 'stretched" so the switchman couldn't get the pin. He had a hard time "balancing" and controlling his speed with air brakes while switching.

Like an experienced driver, driving a car, or and experienced pilot, flying a plane, good engineers develop that "feel" for how the train is handling, in response to the actions you've taken. You want the train doing what you told it to do. And so, you want to see it slowing like you "expected" from a certain brake application, based on your acquired experience and the action you've taken....

I've stopped a cut or two that I knew were already on the ground, just from the "feel", before the crew even knew it.

Railfan or not, doesn't have much to do with it... The foamer I'm describing just wasn't "cut in".... or maybe, just not "cut out" to be a good hoghead...