This note by Ezra Klein on the political implications of false beliefs about income/class mobility is particularly on point:

It turns out that there's a bit of a paradoxical relationship between believing your country has a lot of economic mobility and your country actually having a lot of economic mobility. If you believe that your country is extremely mobile, you're likely to believe the results of the economic competition are relatively fair. As such, you won't want to slap the rich with particularly high tax rates and you won't be terribly concerned about spreading economic opportunity. After all, anyone can make it!