His wife dabbles in bank fraud as a hobby for one thing.
Fraud runs in the family. His wife does bank fraud - Bernie does political fraud, with his agreement to support Hillary (who represented so many things he was campaigning against and who had defrauded him in the Democrat primaries).
If Bernie were for real, he would never have agreed to betray his supporters, who believed in him, and support Hillary, in return for an airplane and a third house.
Bernie is a greedy grifter who will do and say anything to advance what he perceives to be his interests.