These deductions and "welfare for the rich" basically amount to hundreds of billions in lost revenue.
This is well documented, NYT has a good run down: https://www.nytimes.com/2015/03/18/business/economy/taxes-ta...
If you're in the top 0.1%, the actual taxes you pay each year is a far lower percentage than the middle class would pay, due to this unequal system. The rich get richer, and use that money to rig the game further.
Just look at the current tax bill that was passed.