>Do unicorns exist?

In finance, yes.

From Wikipedia:

A unicorn is a privately held startup company valued at over $1 billion.[clarification needed] The term was coined in 2013 by venture capitalist Aileen Lee, choosing the mythical animal to represent the statistical rarity of such successful ventures.[1][2][3][4] A decacorn is a word used for those companies over $10 billion,[5] while hectocorn is the appropriate term for such a company valued over $100 billion. According to TechCrunch, there were 279 unicorns as of March 2018.[6] The largest unicorns included Ant Financial, Didi Chuxing, Uber, Airbnb, Stripe, Palantir, and Pinterest.[7] Dropbox is the most recent decacorn that turned into a public company on March 23, 2018.

https://en.wikipedia.org/wiki/Unicorn_(finance)

The company Theranos was a unicorn too. But their product didn't work, and they bilked investors out of millions. The story is told in the book, "Bad Blood." (Good book, highly recommended)