True, people tend to believe things more if they are stated more confidently. That's basically how many things from scams to conspiracy theories and even cults work. Now with LLMs you have machines that can produce thousands of words per hour in flawless grammar and sounding as sophisticated and confident as you want.

The famous quote "A lie can travel halfway around the world while the truth is putting on its shoes" is older than the internet, so this asymmetry was already bad enough back then and whoever coined the quote couldn't have imagined how much farther it would shift.