Echoing what pugjesus said below, it would be easier to empathize with if it were a sexual thing. Sexy times have gotten weird, especially with the modern internet and the specificity of porn. Most people could imagine how a fursuit might spice up things in the bedroom, not to mention the anonymity of wearing a mask. But few people understand the desire to wear a fursuit for day-to-day activities. I imagine it would be too warm and uncomfortable, and I wouldn’t get any joy or comfort out of it.
Personally, I’m on the live and let live team. I don’t have to understand your lifestyle or your hobbies, nor do I feel the need to justify mine. But that’s probably why you have to keep explaining it to everyone.