Actually you have to consider the one who has everything to lose, they could possible be the most dangerous. They would have to be very careful in executing their plan, you may never see it coming.
I agree with zookool ...
With nothing to lose he has everything to gain, so my money's on him! :-)
Everything to lose because the one with nothing to lose has nothing to lose by doing nothing.
I think when you have everything to lose actions can be more erratic and irrational, possibly dangerous.