Squier is indeed the correct spelling of the family name of the American violin maker whose company Fender would one day buy. However both Squier and Squire mean a knight's apprentice. Modern English had not yet come into being, much less had it settled on standardized spellings, when squiers first began serving apprenticeships to knights. Today many variant spellings of the Squier surname exist because they were passed down through the generations from the time before spelling was a thing, only the squire spelling of the profession's name in common usage has survived the spelling police. This does not change the meaning of the name Squier however. According to Wikipedia in medieval English, aka Anglo-Saxon, the profession's name would have been spelled scutifer, which may explain why one source (sorry, can't recall which) claims that the very first known recorded spelling for the Squier/Squire/etc surname was Scuir.
None of them are famous but I went on the great annual bicycle ride across Iowa again this summer and saw several professional bands rocking Squiers, bass and guitar. Squiers (like a lot of other brand's budget lines) are often good, solid, instruments that will sound great and go the distance for you. There is
no surprise that some pros would stick with a brand that treated them well when they were beginners.
