What if the majority make a law saying "anyone gay or black is to be executed"?
Or "anyone with more than $1 million in assets should pay a 90% tax rate"?
Or "wildfire prevention, nuclear power plant inspection, SEC regulation, should all be defunded in favor of a federal football team with free bread at the stadium"? Maybe it takes 10-20 years for huge-impact consequences to be felt, and in the meantime you get free bread.