Quoted from ultimategameroom:

If this legislation passes it will only encourage millions of people to deal more in cash for transactions of the size that are common in our hobby and NOT make withdrawals and deposits in banks. If it’s going to be passed it will trigger a cash run on banks. No one wants their bank providing their entire years history of transactions to the IRS so they can shake more money our of our pockets. I believe I read the legislation factored in hiring hundreds of thousands of new IRS auditors to handle the workload.