Why do some scientists not accept the reality of psi?

Researchers have explained why some “scientists” can’t bring themselves to accept the reality of psychic abilities, the afterlife, and even that quantum mechanics proves the material world isn’t real. These are some YouTube sources of information:

Dean Radin ~ Science and the Taboo of Psi ~ Link to the YouTube

Rupert Sheldrake ~ Randi denounced ~ Link to the YouTube

Rupert Sheldrake ~ The Science Delusion ~ Link to the YouTube