Just to even clearer. Mitt Romney, when he was earning money in the form of salaried (earned) income, paid taxes on that money at the higher rate. He then took what was left over, and invested the after tax income, in companies. Those companies (if they made a profit) paid taxes at the higher rate on the profit they generated and then paid the investors dividends (if there was enough left over). The Investors (eg Romney) then pay tax (a lower rate) on that “unearned income”.

He earned the money that he later invested. He didn’t win the lottery, he didn’t inherit it, or marry into it. He earned it, and he paid taxes on those earnings.

The tax code gives people who invest (again after tax money) in companies a tax break on the dividends (or capital gains) that they might earn.
The reason for that was to encourage people to invest in companies. Companies that hire employees. Companies that contribute to the GDP.

If the tax cost to investing were to double, what would be the unintended consequence?