Bratty Justin Bieber heading for career ruin?

The increasingly arrogant pop prince Justin Bieber took bratty to a whole new level in a four-and-a-half hour deposition video recorded last week in Miami after one of his bodyguards was accused of roughing up a photographer.

The highlights released by TMZ include Bieber dropping the F-bomb on a soft spoken court reporter, failing to remember who hip-hop sensation and early mentor Usher was, and showcasing his vocabulary struggles by noting that he became famous all by himself on YouTube and was thus “detrimental” (rather than instrumental) to his own career.

VIDEO: Bratty Bieber's awful deposition moments

Add this to him peeing in a mop bucket, trying to get in a fight with paparazzi, a DUI arrest, and egg-throwing allegations -- the list goes on and on -- and one may wonder who exactly is the once squeaky clean singer's fan base these days?

“Someone who likes to watch train wrecks or planes crashing,” Eric Schiffer of told FOX411. “The worst is absolutely yet to come.”

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Schiffer said the longer Bieber takes to clean up his act, the harder it will be for his old fans to forgive him -- and buy more of his stuff.

“Until he grows up and awakens to his lack of respectful, dignified behavior, then protecting his reputation cannot be done,” Schiffer said.

For now, it seems Bieber is convinced he's just a victim who has been "harassed." On Monday, he posted a tweet after various media outlets published stories about the deposition.

But the signs of Bieber's once skyrocketing career plummeting to earth are already there.

In March, Bieber was reportedly forced to cancel concerts in Portugal due to empty seats, and later in the year his ticket sales for an eight-show tour in Australia also tanked.

WATCH: Bieber's most arrogant moves

In December, Bieber’s concert film “Believe” became something of a big box office bomb, bringing in just $4.5 million on its opening five-day run – a mere fraction of the "Never Say Never," opening in February 2011 which grossed to $29.5 million in North America and posted a domestic gross of $73 million, making it the most-successful concert film of all time in the U.S.

But even if the once devoted Christian reaffirms his faith and embarks on a mea culpa tour, he may struggle to return to his previous heights. And while many child stars struggle to transition into the adult world, love or hate her new direction, Miley Cyrus is at least serious about furthering her career, and isn’t expecting fame and fortune to be handed to her on a silver platter.

“Miley has not spun out of control. She is in control and pushing the envelope for attention. It is the opposite of out of control and what is happening with Bieber,” crisis communications expert Glenn Selig observed. “Justin Bieber needs to grow up! But in all fairness, his success was built on him being a kid and a teen and he's getting older. In his mind he may feel like he's fading. But he should see it as evolving and growing in the business.”

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But digital communications expert and CEO of Quantum Networks Ari Zoldan says the Biebs still has a huge base of die-hard youngsters.

“A majority of his Beliebers defend him through thick and thin. They’re not going anywhere,” Zoldan added. “I’m willing to bet the farm much more is coming down the pipeline. He is still in court and continuously getting in trouble with the law. He is continuing a downward spiral with at least one ‘episode’ a month. If he is smart he will correct his ways and get back on track."

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