I like your comment Ryan.  The idea that that capital gains tax is used to encourage higher investment by providing a low tax rate, is a fact.   It's not MY theory though.

My general observation on the need to encourage investors is:  So they raise the tax of realized gains.   

Name me something else a person with a high disposable income,  can do that will give you a return with NO WORK at all.   Investors won't leave the market based on tax's if they are still getting a positive return.   What investors migh get is a fractional drop in the 'expense ratio' of the investment managers to offset the extra cost of tax's.     

People will make adjustment no matter what the new tax plan looks like.