Holloway, who coached Zaha at Crystal Palace before the talented winger moved to Manchester United this season, claimed the England international has 'more natural talent than any footballer I have played with or managed'.
But the former Crystal Palace and Blackpool manager warned Zaha that he must start growing up and quickly show why United paid £15 million for him midway through last season, otherwise he could be labelled 'a waste of money'.
"Wilf has gone from being a big fish in the small pond of the Championship and is now a minnow in the shark-infested waters of the Premier League," Holloway wrote in his column for the Mirror.
"And it's been a struggle.
"I hope he uses his sabbatical in South Wales to show United exactly what they are missing.
"Believe me, he is one helluva (sic) player. And he is also a terrific lad, a manager's dream, in my experience. So, I was surprised by reports during the week that he had been dropped to the bench for a reserve game because he turned up late.
"That isn't the Wilfried Zaha I know and I am sure that he would not have shown such a lack of respect to his club on purpose. But, as a manager, I can't condone any player failing to get to a game on time.
"And, again, it's all about attitude. Or lack of attitude.
"I will always be grateful to Wilf for the role he played in helping Palace to win promotion to the top flight when I was the manager at Selhurst Park.
"And that's why I have his best intentions at heart when I say the time has come for him to take stock of his life and career and grow up a little bit.
"Because, believe me, there is nothing more tragic than unfulfilled potential."
Holloway expressed regret at not preparing Zaha more ahead of the latter's move to United but claimed the Ivory Coast-born winger could not blame anyone else for his lack of playing time at Old Trafford.
"I wish now that I had taken him to one side after a Crystal Palace training session and warned him that it (the United transfer) wasn't the end of his journey to the top of the game, it was just the first step," the 50-year-old said.
"Wilf is joining Cardiff on loan after playing just 28 minutes of Premier League football in five months at the champions under David Moyes.
"No doubt, some people will now label the lad a waste of money. But... Wilf has got the world at his feet.
"At the age of 21, he has more natural talent than any footballer I have played with or managed during a lifetime in the game. What he has got to prove now is that he also has the temperament.
"Wilf has only one person to blame for the fact that his only start in the famous red shirt so far was a Capital Cup tie against Norwich in October: Himself.
"He hasn't been a regular in the United team simply because he hasn't done what his manager has demanded from him."
