I read articles periodically about people getting 'traced' using bitcoin while buying things on the 'darkweb'..... And considering how tor/bitcoin is supposed to be 'untraceable'.... how is it possible these people are getting caught... or rather 'why' do you THINK they are getting caught?
Its more down to IRL mistakes which leads to somebody's DNM activities being uncovered. Not online opsec such as not tumbling or using Tails etc.
Also TOR and BTC is not untraceable.