Yes, in reality, most restaurants do fail that are self-owned. And a lot of chefs, cooks, kitchen workers, etc. are not right in the head anyway. But Sam was a drug addict, so he'd be suitable there.
And notice Wendy didn't demand back the drugs from Sam to get her money back? I suppose Sam just took the drugs and either snorted them all or used them to live off of for a few months. Then he was probably hitting bottom again and looking for another lonely single mom to take advantage of.