Asklemmy

Hermeticism is a gnostic esoteric system and like all gnostic forms, it implies that there's an "unknown" reality that can be disveiled through revelation. You have a perceived reality that is fake and a "real" reality that is hidden from you. This already sets the ground for conspiratorial thinking.

The second element is that hermeticists in the 18th century were relatively rich and powerful men who met in secret societies, which was something everybody did, but they also had the money to build monuments and hide their symbols in plain sight. This created the trope of a secret congregation of powerful men into esoteric shit who plot to take over society.

A lot of conspiracy theories reference Hermeticism blindly. One example is Flat Earthism, they use a lot of Hermetic concepts of the firmament to describe why the world is flat. Hermeticism is fundamentally the progenitor of modern astrology, alchemy, 'witchcraft' and so on.

Like the other commenter said, hermeticism relies on the belief there is an "unknown" reality that can be unveiled. This was a core tenet of ancient Greek religion and explains their tendency to practice divination, in a way a lot of modern woo-woo stuff is directly lifted off of a bastardization of ancient Greek religion. Its very interesting to do a meta study of conspiracies, people are tapping into shit they have no clue about and are rethinking thoughts and ideas made 3000 years ago by a drugged out woman in a cave filled with lead. Hermeticism was also a very popular system of gnostic beliefs during the medieval era, quite a lot of Arab philosophers for example believed in a variety of gnostic religions, e.g. Sabianism which is referenced in the Quran as being 'people of the book', a group of people along with Christians and Jews that should not be harmed but taxed.

As Marx said, "The tradition of all dead generations weighs like a nightmare on the brains of the living."