“Fanboi” is a fairly common insult used by non- / anti-Mac users against those whom they perceive as having blind devotion to the Mac.
Yes, fanboyism exists for Macs, just as it does for many other products/pastimes/theories.[1]
However, in a class of Mac users (namely, those who have been using Macs since at least the 90s) there is a sensible and defensible reason for why — if it exists — it does so. (Although, that said, in my experience the longer someone has been using Macs, the stronger the attachment but the less preachy the approach.)