No offense to red heads. Some of my best friends were born that way, and heck, I even married one.
Well yeah...you gotta lock that down.
Back on topic: Most people just go on their individual perceptions (which are inherently biased and rarely correct). Ultimate is FAR, FAR, FAR more popular than disc golf.
IIRC I read somewhere that it's under consideration for being added to the Olympic Games (which doesn't mean it will get in, but means it meets the criteria of worldwide popularity and participation). Disc Golf is far from that marker.