"The Dunning-Kruger effect effect occurs when a person's lack of knowledge and skills in a certain area cause them to overestimate their own competence Squeak up.
Probably cause they have tendency to speak louder than the rest of the crowd. Especially on the social media. So, they seem to outnumber the ones who are not afflicted by that, but in fact they are really just more visible. If you're not confident, you'll stay low profile.
I think it's very easy to fool yourself in trading. Many of the people here who are trying to fool others actually fooled themselves first and still believes their own nonsense, even though their broker account tells a different story. Then you have those who never made it or at least didn't make it big, but which enjoys lecturing and acting the role of the guru - maybe gathering a small crowd of followers which makes them feel good about themselves.