As with every technology, TOR too can be used for good and bad with the good often not being shown to people.
According to TOR's official website,
Journalists use Tor to communicate more safely with whistleblowers and dissidents. Non-governmental organizations (NGOs) use Tor to allow their workers to connect to their home website while they're in a foreign country, without notifying everybody nearby that they're working with that organization.
A branch of the U.S. Navy uses Tor for open source intelligence gathering, and one of its teams used Tor while deployed in the Middle East recently. Law enforcement uses Tor for visiting or surveilling web sites without leaving government IP addresses in their web logs, and for security during sting operations.
Apart from this, you can also set up a website on the dark web to avoid revealing your location or who is behind the site, use it for communicating with anyone when you need to hide your identity, anonymous bloggers, government officials and the like would greatly benefit from this.
Note: This guide first appeared as a blog post on my website at sudaisasif.com, feel free to check it out and other posts!