You are totally right. But hear my case. What if you were doing arbitrage between CEX and P2P DEX (paid in fiat). Of course coninjoining in between and separately from your stack. The profit margins are just too high and after all someone needs to add liquidity to those kind of DEXs.

Because of the fiat payments, there's a high chance the bank snitches on you and someone comes asking questions. How do you justify those? And of course there's the trace of buys in the CEX anyway. So I would like to find the cleanest way of doing this and don't particularly care about paying taxes for those gains (because the risk of not doing so is not worth it).

If it was only buying Bitcoin on P2P DEX it would be stupid to declare anything of course. But this case is different. Or am I missing something?