I can't answer for sure, but in the case of very rare first names such as Hyatt, it often is the case that it used to be a last name or a maiden name. That said, it could also be a bad spelling or Wyatt or perhaps Hyatt was a very rare first name in Europe and when last names were created, the last name of Hyatt was created out of the first name or it was the name of a small town or castle.

I do remember reading about Hyatt Hotels and how they were the first to be near airports and they were pretty soundproof so they succeeded in helping business travelers sleep well. (^:=

Lastly, I too was made fun of in school as "Hi It!" I shrugged it off as other kids had it worse than I. I recall a kid named Dusty Rhoades who was made fun of a lot.

take care,

Jonathan Hyatt