Like most in the food service industry, you can make okay money, but generally not great money. Of course, if you're the head chef of one of the top restaurants in New York City, you could be making an excellent living. That's the exception rather than the rule.
Considering that most chefs work in more modest establishments in more modest regions, you're looking at a salary of $40k a year on average, maybe $10k less than that if you’re still a sous-chef in the process of working your way up to the "big money." When you think of a chef, you probably instantly envision the guy with the tall white hat working in an upscale restaurant, but you also need to realize there are chefs working in dumpy diners or fast food joints (you don't want to be serving Krabby Patties like Spongebob Squarepants), in the kitchens at grocery stores, in cafeterias, etc.
"I'd like some more, Sir."
There are many different avenues for chefs, but few of them are super-lucrative. At least you can save money on meals by snacking on scraps.
Here's what a typical Profit & Loss Statement might look like for a restaurant. Notice that the restaurant had roughly the same operating expenses in 2010 and 2011, but had a down year in 2011, bringing in nearly $500k less than they had the year before. Wouldn’t be so bad if there were no costs, but look how barely the place scraped by in 2010 even with good business, and then look at what happened to them when their profits dropped off: