Egg yolk contains fats, proteins and vitamins such as vitamin A, vitamin D, vitamin E and biotin. Hair itself is largely made from the structural protein Keratin, and egg yolk contains amino acids that resemble
Your hair and your scalp don't absorbs vitamins.
Your hair is a dead byproduct of roots production, who absorb nutrients from the blood, the nutrients you have ingested
Any homemade remedy will theorically always be better if the comparison is a harsh industrial shampoo