Charles Xavier likely had a genetic predisposition for baldness, which was only accelerated by the activation of his mutant powers. It is a side effect of his mutant powers, not a trait associated with vast psionic ability in all mutants.
Cassandra Nova, genetic twin to Charles Xavier, but actually an alien invader seeking powerful genetic material to copy.
When the Mummudrai, Cassandra Nova copied Charles' DNA in the womb, she too would eventually lose her hair, the same way Charles did, bolstering the idea that Xavier's powers were linked to eventual, premature hair loss.
Cassandra Nova is Professor X's lost twin who died in the womb and is responsible for the 16 million mutants that were slaughtered in Genosha. She possesses similar telepathic powers as Charles Xavier and several latent abilities as well.
Cassandra Nova can also induce mutants to undergo secondary mutations, with varying results. Emma Frost's secondary mutation offered her a diamond-like conversion of her physical form.
The Mummudrai are noncorporeal parasites, composed solely of emotional energy born from the astral plane of existence. The first and most notable member of the mummudrai species to appear on panel is Cassandra Nova.