@PipedPiper do you "understand" why some people are afraid of enclosed spaces, or open spaces, or long words? You might think somebody being afraid of heights is more "understandable" than one of those, but if you've met someone with acrophobia you'll know it goes far beyond the fear most people experience when they are high up. Kinks and fetishes are as irrational as phobias are, some might seem more "understandable", but, at the end of the day, they're just specific conditions that arouse you super hard for no apparent reason. You might think feet are cute and all, you might appreciate them as part of a hot person, you might even "understand" footjobs, but if you don't have a foot fetish, you'll never experience the same arousal from them.
Point is: don't try to "understand" a fetish logically, your dick/pussy either likes it, or it doesn't. There are situations where you can eventually "get it" when you see a specific take or just developing it over time, but even then it has nothing to do with looking at it logically.