Demo bid lost, help me out

I bid on my first demo job. The house was a single story 36x26 on a crawl, block exterior walls and a car port off the back 12x20 (wood) and a few interior items. Interior walls and floor are all wood and rotten, and the roof is seriously like a 2/12 pitch. Surrounded by trees and bushes, this thing was dilapidated. Roof caving in, floor cave to the ground, been siting for 20 years. on a well and tank, with and old fuel tank for heat. I bid 5500 on the demo and removal of debris and 1500 on bringing the dirt in to level back off. Fill dirt is 2.50/ton and trucking is 8/ton(roughly).I was under bid at 4800 for everything, demo and dirt. Was my price that far off or was his that far under.