Why do guys named Timothy go by Tim when they could go by Moth?

Why do guys named Timothy go by Tim when they could go by Moth?

Commentary:
Well, wouldn't it be amusing to hear someone say, "Oh, hi there, Moth!" 🦋 It's a shame we're missing out on potential entomological nickname possibilities! Maybe "Tim" just isn't ready to spread his wings and fly as "Moth" just yet. 😄