I have a bitcoin wallet that is regulated by our government if ever i get questioned about being instant rich i would present this as evidence that i earn my money through bitcoin whenever i get wealthy with it. I have no problem paying taxes in fiat but our government has no laws about taxing bitcoin users. So i wont.
Which country are you from that doesn't tax crypto income? Is your income even tax-free once converted into fiat? If so, sounds like the quite the tax haven for crypto users.
As for @OP, I think so long as you keep reasonable records then nobody will question your wealth, nobody expected bitcoin to explode like it did, so I doubt they will be as thorough as they would with other income records, even if you just log your purchases, and then identify the value at that time on coinmarketcap, that will likely suffice.
There is no regulation yet on crypto in some countries so people who are earning can really enjoy their entire profit.
But, the sooner the government sees the demand of crypto and the money going in and out, they will surely tax those people who are earning, one
county I know that does not tax bitcoin is the Philippines.