In America Tor is mostly used (other than as a curiosity) for drugs and child porn. The former I could care less about, while the latter is indeed creepy. It's also occasionally used for private communication with journalists, a numerically less common use but a politically critical one. While I strongly detest child porn, I equally detest drug prohibition and journalist and whistleblower harassment/censorship.
In Iran? China? Saudi Arabia? Russia? In places like that Tor is used for dissident communication and private correspondence with people overseas. In those places public opposition to the ruling regime can itself be a crime.
There are also authorities including police and intelligence personnel who use Tor -- very ironically to hide from criminals. For example, an undercover cop might use Tor to hide their correspondence with the police from digital snoops in the employ of a criminal organization they are infiltrating. Some organized crime outfits are very sophisticated, making undercover work actually require a degree of 'op-sec' on the part of the agent. Compromise can be fatal.
Tor is a gun. Criminals use guns but so do police, hunters, and people legitimately defending themselves. In America you could probably defend Tor and other crypto tools on second amendment grounds.