This is just my observations:
The float will not hold the pot up so if the pot is in deeper water then the rope length , crabber will never find it. I've snagged pots in 30 feet with only about 15 feet of line on them.
I've seen pots dragged into deeper water then set by sailboats , barges pulled by tug boats , storm debri ( trees , etc ) and fishermen's anchors.
Floats get cut off by power boat props. Near Annapolis - I see speed boats run through the crabbing areas and never veer left / right. Hard to believe they lucked into a wide open path.
Often after a nice summer weekend - if I fish Monday , not uncommon to see cut off floats drifting along with current.
Now / then a rope or knot breaks - leaving pot on bottom. Very strong storm surge can move pots sometimes.
Hate to bring this one up but vandalism of pots by cutting line is not unheard of.
IMHO - these are 5-6 main causes to lost pots.
One thing that causes problems is how pots move with the crabs. Boaters might not be watching for pots in deeper waters often crabbed in early and late season.
What could be more mundane than dying of old age or of natural causes when there is death by misadventure to be pursued ? Skip