It's the Marie Antoinette effect. Even though the quote is likely apocryphal, the point behind it is that she was so unaware of the people's level of starvation that she genuinely thought that eating brioche ("cake") was a viable alternative for bread, which they did not have.
You do not want politicians like that.
Oh, people working 40 hours a week can't afford rent and food? Why don't they just eat less and get a second job?
They will likely never experience many of the problems that the general population does.