Superstition? Or what caused this?

Imagine how dumb you'd feel if you were the only person to walk under it and it fell on your head and kill you.

You'd be so pissed.

Honestly I do this kinda thing all the time. Make minor adjustments in my life to reduce risk. Like if I'm going on the subway and the escalator is stopped, I'll just walk up the normal stairs, since there is a minor chance that an escalator could collapse

In this instance, it takes nearly the exact same amount of time to go around the pole and there's no risk of it falling on you or whatever.

I don't think it's fear about structural integrity. It looks like you'll hit your head if you keep to the right like many people will. Especially if someone also approaches from the other direction. Maybe also cyclists?

Avoiding people coming from the other direction maybe?