Most of these people aren't true sadists, they're infamy seekers. They use ideologies like sadism, accelerationism, Satanism, and Nazism as a kind of mask. Their public perception is everything to them, they want to be feared and seen as evil, dangerous, or crazy.
In reality, they're just average "losers" who get a dopamine rush from finally being noticed and feeling important, it’s like a drug to them, this feeling overpowers any guilt they may have. Once they're stripped of this perceived power, they're left with the guilt and anxiety that will eat them alive for the rest of their lives in prison.
TLDR: if they were actually sadists they wouldn’t flaunt their crimes online for attention they’d do it in private, they’re just attention seeking losers using sadism etc as a mask to make themselves seem as more than the average pedo loser.