Opening a restaurant is hard work, exceptionally long hours, and absolutely taxing- financially, mentally, physically, and emotionally. But assuming that the paperwork is right, and the money is there, and there is a proper source of customers to support the business... sometimes new restaurants struggle because their owners aren't ready. They aren't ready for the stress and long hours, and constant new problems. They get over worked, don't sleep, and are worried constantly. Sometimes this pressure can change a person's attitude. They snap faster, they yell more, they push people away. They aren't as understanding or encouraging.
While this doesn't directly cause a ship to go down, what is does do is demoralize the staff. People start dreading coming in to work, people look for other jobs, and then the boss is trying to find more staff to train, causing more stress. There are a lot of ways the spiral out can happen, so I think it's important to remember that staff is massively important, and so is their happiness.
I would truly suggest being on a restaurant's opening team before opening your own. Just to be aware of the demand and the stress it places on people and how to stay positive. Some people say "people don't quit jobs, they quit bosses" and having a dedicated core staff can really make or break a restaurant- especially if it is new.