No need for studies. As regulation increases with surveillance it's an ever increasing number.

Risk of confiscation today is two or three orders of magnitude higher than 5 years ago. If not more!

Soon everybody will know someone with a frozen account or transaction. It's inevitable.

My recommendation: Use credit cards for digital payments. More private than BTC and if KYC'ed a near zero chance of failing transactions.

For everything else there is Monero or cash.

Everything else is nearly worthless.

Imagine you have $1B. But you can not spend it. Is it really worth $1B?

This concept applies to all non-fungible coins including BTC. If you really think BTC NGU won't be broken in the future by the BTC ETF and pay your taxes on it