You opt out by not reporting the sale of your asset held for 1+ year on next year's filing, and you do it in a private transaction where KYC does not apply, whatever that means to you.

The private transaction bit though... You then either live off the cash or have a traceable transaction going in to your bank account. Enough of those would raise questions. I guess cash can work, but only to a point. Recent example, new tires on a truck for $1500. Not very many businesses are going to accept cash for that. I'm not at a point where I need or want to sell BTC, but for sure someday I will.