Well some mixing services have 2000 up to 5000 btc which is an amount much higher than any hitman can ask for doing his dirty job.
Riiight.
I'd bet my life that every single hitman on the dark net is an 11 year old scammer.
Do you accept 5-6 BTC to murder a stranger and potentially spend the rest of your days behind bars. Or do you accept 5-6 BTC, or perhaps half upfront, and, like, not do it?
Golly, that's a poser.