One piece of evidence for the above claim: https://www.icij.org/inside-icij/2021/03/u-s-sanctions-ukrai...

North Korea would beg to differ, having amassed billions in violation of International sanctions. [1]

[1] https://www.investopedia.com/news/what-north-koreas-role-bit...

That the wealthy have many other avenues for exfiltrating money doesn't change the situation that crypto is an extremely effective method for doing that. A lot of people need as many channels for the exporting of wealth as they can get.

Iran's rulers might or might be oligarchs but the use of bitcoin by the Iranian state[1] seems like good evidence that crypto isn't just for the little guy.

[1] https://www.reuters.com/technology/iran-uses-crypto-mining-l...