Yeah, that “They must think you’re stupid” line began to wear thin with the very first hearing.
The argument that only stupid people vote Republican has been a staple for the Democrats since 1980. Since then they are 2 for 5 in Presidential contests, and their only two wins came because Perot siphoned off the Republican vote.
People don’t like being insulted. The Democrats have made insulting the voters a central part of their appeal.