Do you declare your NON-KYC Bitcoin to your tax agency?

I was wondering, the whole purpose of non-kyc bitcoin is for them not to be tied to your identity, so we keep them on cold storage and wait. So if they are not tied to our identity, I think that most of us don’t declare them to our national tax agency.

The question is, what happens if in the future, bitcoin price goes very high and we end up with money enough for, let’s say, buy a house.

Of course we won’t be able to justify that amount of money. Even if we don’t sell our bitcoin for fiat and the house seller accepts bitcoin, you’ll end up being owner of a house that “you can’t afford” according to your declared income.

This got me thinking, will in the future (let’s say 10 years) our NON-KYC bitcoin only be usable for groceries, gas and small cash purchases? If not, how could we in the middle of the way to the moon, suddenly declare “oh I forgot, I had this bitcoin for a few years”.

Thoughts?