Why would someone start a catering business?

If I understand your question, you are asking why someone
would start a catering business.  I have edited your question to say
this.

The most important reasons for starting a catering
business are these:

• Perceived demand.  If a
  person is going to start a catering business, they have to think about whether there is
  demand for that particular service in their community.  You would not want to start a
  catering service if you did not think there was enough demand (if there were too many
  caterers already or if people in your area were too poor to afford caterin, for
  example).


• Expertise and interest of the entrepreneur.  In
  order to start a catering business, you would need to know what you are doing and you
  would need to enjoy that line of business.  So one of the major reasons to start a
  catering business would be personal--because you are good at it and you like
  it.

So there are two main reasons--you would
start a catering business because you think you would be good at it and because you
think you could make money.