Sanders never said he supports a 90% tax rate. He just said that's what it was back in the day under Eisenhower.
You're just making sh*t up basically.
“We haven’t come up with an exact number yet” for the top tax rate “but it will not be as high as the number under Dwight D. Eisenhower, which was 90 percent.”
Sanders was specifically asked if he was opposed to a 90% tax rate for America's income-earners. He flatly said "No."