In my opinion it does not matter what you do with the money. You first have to work out what the Capital Gain is on the BTC

and then you can buy whatever asset you want. If you earned say $2000 worth of BTC or you traded and your profit was

$2000, then you have to pay Capital Gain on that first and then you can buy the car or whatever you want to buy. 

Also remember that you are paying VAT on that purchase.