Keep as much as you can in the bitcoin world, then you only need to declare whatever you have changed into fiat cash, maybe so little that you don't have to pay any tax at all.
That throws out the baby with the bathwater, doesn't it? Admittedly a large proportion of your tax goes on defence and military spending, but you're also paying to have your rubbish collected, have your community centres maintained, have the courts run...
No, the baby is dead and rotten. It doesn't cost 16 trillion dollars (although I assume you are British, so it's some other figure) to take out the trash, clean up the parks, and pay judges. As if those things couldn't be done more efficiently by the private sector anyway.