It’s the nature of the beast (public ledger).
KYC is the biggest pain IMO.
Discussion
More than KYC, regulatory capture in general is the greatest unaddressed risk. Capture of exchanges, pools operators, and hashpower providers. Forced doxxing of users. Forcing pools to only include transactions where sender and receiver are both doxxed. Forcing hashpower providers to only send their hashes to the compliant pools.
If the majority of the hashpower is caught up in this, they can not only exclude non-compliant transactions, but can also orphan valid blocks added to the chain by non-compliant nodes in unregulated jurisdictions.
Profits for noncomplying miners would rise relative to compliant miners, resulting in more noncomplying hash rate coming on line as well as some compliant miners defecting. This is Bitcoin's security model. Always has been.