I have made multiple accounts on Nostr and zapped myself tens of thousands of sats before. Now I have multiple keys and wallets that I can use to zap multiple other posts to make it look like certain posts get more zaps. Posts I control ofcourse. I then just keep all my sats flowing under my control. And when I need sats I can just make a post and have my zombia accounts zap em back to me. It might not be money laundering exaxtly but the principals are still the same. You texhnically dont need multiple wallets but I find it better for privacy