People with 100+lb bikes- what the heck are they?! I assume they're Xtracycles or cargo bikes of some kind?

Personally, I view the issue in the opposite direction: The bike that can carry the most weight gets the biggest bragging rights, regardless of its weight.

Edit: I like something reasonably sporty- mine is right around 30 lbs with a pair of panniers, flat repair supplies, lights, etc., plus maybe 10 lbs of 'stuff' in the panniers on any given day.