The Dark Web is just another part of the Internet but, as you state, requires use of special protocols such as I2P or TOR (the onion router).

And just as certain as there are illegal activities by the Big Banks and mainstream politicians (in the US and other countries) there are also illegal activities on the Dark Web.

However, it's just another Internet -- it's just not censored, and it's harder to track your activities.

Also, it's not completely secure, as the FBI is known to host their own servers to capture traffic.

I2P is probably the only protocol that I believe is completely safe, as packets are passed along without the host receiving it knowing who it is for. It's a decentralized trustless system, like cryptos.

You do need to be a lot more careful on the Dark Web, due to viruses, etc.

But, it's just a repository for information, just like the regular Internet.