Odds of Hanging On
In the immortal words of Boromir, one does not simply keep a restaurant open. It's a fairly well known fact that most restaurants fail, and anyone who tells you otherwise is either a compulsive liar, or the manager of a competing pizza parlor hoping to lull you into a false sense of security.
Here are the cold, hard, inedible facts: 60% of restaurants fail within a year of opening, and 80% fail within five (source). Not what you wanted to hear? Yeah, not what 80% of aspiring entrepreneurial food service managers wanted to hear either.
If we had to guess, the 20% who survived probably had a few things in common, like lots of experience managing restaurants and a bulletproof business plan. Do your homework, work your butt off, and who knows? Maybe you'll prove the naysayers (and those pesky statisticians) wrong.