Taxed on cyrpo gains of course. But what happens when crypto can be exchanged for goods?

So obviously if you buy lets say Eth at 3,500 and sell at 4,000 you will be taxed on the gains from coinbase or whatever medium you use.

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When we get to the point where crypto will be accepted as payment for groceries, plane tickets, etc. Do you also get taxed on using crypto as payment? Lets say you bought 10 bitcoins in 1014 and were able to buy a tesla with your bitcoins. You pay your .5 bitcoin to Tesla, do you get taxed on that .5 bitcoin payment since the value difference from when you bought to transferred is immensely higher?

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Cheers!