Since Nico Rosberg's 2016 breakthrough, Hamilton won three world championships on the trot to add to his existing tally of three titles.
"God may be with him, but he is not God."
Briatore agrees with that, telling Italy's Autosprint that the Mercedes driver has a clear car advantage.
"Lewis wins not because he is the best driver, but because he drives a fabulous car," the former Renault and Benetton chief said.
"He is beatable at least. He is strong and makes few mistakes, but if someone manages to put pressure on him, it would be a completely different story."
Meanwhile, Briatore is still involved in the management of Fernando Alonso, who is eyeing a full-time return to Formula 1 for 2021.
"I talked to Fernando and he will only return if he is with a top team, which means Ferrari, Mercedes or Red Bull. Otherwise it makes no sense," he said.