I am not sure the IRS can really do anything about purchases. Technically you should already be paying a sales tax. So it would be double taxation. Definitely need a good atty Tho.
The blockchain is public and transparent. Using exchanges with KYC and ID verification, it won't be difficult to link purchases to individual citizens and hit them with taxes.
There is a law that you can't pay tax twice on the same purchase. It's not like you sold a stock and then bought something with the cash. That's 2 transactions. There will be a lawsuit
purchase of stock (any securities) is not taxed. Profits are. Loss is deductible from profits. Get yourself a CPA. Every honest citizen must pay as little taxes as possible.
Who helps your gov to write the tax law? The Big 4 and CPA lobby groups. Now you know, why it's so complicated. Did few trades cap gain/loss is nothing complicated if you can read