Pardon the vulgarity, but back in my Army days, I would have replied:
"Because F you. That's why".
Your photos are cleary very nice.
Another saying I like to use is:
"if it's stupid, and it works, it's not stupid".
I used to get the same kind of questions when I was shooting with my 70-200 f2.8 on my little rebel XT. When they saw the photos, they stopped asking stupid questions.