The trick of the Dark Web is that it reroutes you through other servers so it is virtually impossible to pin point your location.
It also masks your identity and keeps no record, so that it is pretty unhackable.
You use it when you do sensitive online stuff, like banking. You use it to connect and do your business and then disconnect.
If you use a regular browser it can be hacked. One can trace the I.P. you are connecting from, and might get into your computer.
Let’s suppose you Bank with Moneybags. You connect via a regular browser and do what you do.
A hacker catches you and shortly after sends you an email which appears to come from Moneybags telling you that you must change your password.
You log on, the hacker is with you, and there’s your brand new password in their hands.
This is why you use the Dark Web.