"the US already gets 70% of all its taxes from the top 10%"
The rich are getting richer not because they pay too little in taxes, they're getting richer because they rig capitalism with the help of their buddies in D.C.. Level the playing field of commerce, and you'll start to see some redistribution of wealth.
And there's nothing unfair about the top 10% paying 70% of the taxes, in fact that statistic doesn't include the relevant data to even see if it's fair. It's not their share of total taxes that is relevant, it's what percentage of their income vs the percentage ordinary people pay that matters.
For example, if that 70% only represents 20% of their income, then 70% isn't enough, they aren't paying a fair share.