He does drink a lot, I'm pretty sure he got a DUI.
Also, although he was the 'go-to' midget, he missed out on the quintessential midget role of his time, Willow. Warwick is an ugly midget best suited for costume work, too young for Wizard of Oz and Under the Rainbow, too ugly for Willow. He'll always have Star Wars, though.
I'd say he's miserable but has no right to be. Fuck, he was R2-D2 for christ sakes, that beats the shit out of Willow.
edit: Apparently he was Willow. I hated that movie, disregard this post.