There are reports out of "woo-land" that are impossibly large for F&B. Bone structure wouldn't support the weight. Rather than say "liars", I'm going to say "I'm not sure what they saw, even if they perceived it as bigfoot."
I would say that 14 foot range is about right. A witness described one giant BF that would occasionally visit her dad's property ducking under a branch they measured at 14 feet. That doesn't mean it HAD to duck, might have cleared, might not have, but it stooped slightly when it went under. I watched her interact with a group of other bigfooters. I began thinking she was just a "groupie" wanting to fit in. After 4-5 days in the field, I came away thinking she was the only one of the bunch that was legit, the rest were slightly delusional. I'm inclined to go with her report.
The first one I saw .. I don't think was 14 but I think it was some amount over 10 because BFs have legs shorter, relative to torso length, than ours, and it was crotch deep in water that hit me right at chin level .. 4.5 to 5 feet deep. The math simply requires it to be over 10 feet, possibly nearer 12. If that is the one that left the tracks I saw 2 years earlier, it leaves 24-1/2 inch tracks. When I talked to Henner Fahrenbach a few years later he said the biggest tracks in BFRO's "library" that weren't debunked were 27 inches. So .. math, not concrete evidence, but again, backing into that same answer.
One of the Canadian guys, I think either Dahinden or Green, mentioned having some initial doubts about the authenticity of the Nor Cal (Bluff Creek, etc) tracks because the shape was different than what they were used to researching in Canada. Those northern tracks, they wrote, were comparitively longer and narrower, and had the slightest hint of curve .. but not an arch! .. rather than the very broad shape of the nor cal style tracks. What they describe for tracks matches what I found. I wonder if what I saw, and the tracks I saw, weren't from a long distance traveler rather than a resident.
That said .. unproven. Should be considered but also should be taken with a substantial grain of salt. We are still in discovery, not in study.