As everybody knows, he was the child superstar of Diff'rent Strokes, a TV sitcom that ran from 1978 to 1986.
Yeah, the show was saccharine and contrived, but it entertained us. All the while, Gary suffered from a congenital kidney disease that stunted his growth. All the while, his parents misappropriated the millions of dollars he earned on the show. In the end, he was famous but not wealthy. That's a nasty combination. The public never forgot about the cute child star, so he got all the press any time something in his life went wrong, and yet he had few of the resources to shelter himself from the mockery.
Looking back at the history of Gary and his child co-stars, it seems they gave up a lot in order to entertain us.
Everybody's got a special kind of story, but Gary's real story never seemed funny. Rest in peace.