With his third place finish in the Iowa caucuses, Marco Rubio appears poised to claim the mantle of the "serious" Republican candidate in 2016. So now might be a good time to discuss that Rubio wants to do something that is, even by GOP standards, rather wild: He wants to scrap all taxes on interest, dividends, and capital gains from stocks. This means he wants to get rid of all taxes on income from wealth ownership, and only tax income from labor — i.e.