How do people like him still have so much money?

He made enough money for a lifetime.
Michael Jackson probably left him another pile of money too.

considering his money was only released when he turned 18 im sure he had a good upbringing and lived within his means

i remember he got paid 5 million dollars just for doing GETTING EVEN WITH DAD in 1994 and got 10% of the box office receipts of home alone 2 lost in new york which were huge that year in 1992

essentially he won the lottery in his childhood and is spending his adulthood living off it.

I thought his parents were taking his money when he was a kid?

Yup......he was the biggest child actor of all-time (since Shirley Temple). People have to realize how big 'Home Alone' was (still is today). Highest grossing movie of 1990 and spent like 12 weekends at #1 at the box office. Unheard of today.

After 'Home Alone', then studios saw him as a huge, bankable star. 20th Century Fox made massive money on that movie. Culkin got huge million dollar paydays for films like 'Home Alone 2', 'The Good Son', 'Getting Even With Dad', and 'Richie Rich'. If IMDb is accurate, his salaries were over $26 million just for those films.

That's 20 years ago. If his family, advisors, whoever just made some simple investments that were waiting for him - he's clearly set for life. And who knows what kind of royalties he gets even today.

Culkin's net worth is an estimated $15 million today. Looks like his parents didn't squander it all away.

He hasn't acted since he was a teen he stopped acting again last him he was acting was 2004.

I wonder what his residual's are today? Home Alone, especially, was such a big hit, I wouldn't be surprised if he get's a fair amount from that and the sequel (someone correct me if I'm wrong). As of this post, I typed in what his networth is and it seems $15 million is his networth, which is nothing to sneeze at at all, considering he hasn't really been acting much and certainly isn't in the mainstream.

All things considered, if he handles his money well, he'll be ok.

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Living within his means.