Why stand for public office?

People use to stand for public office be it as a local councillor or as the member of parliament because they wanted to do some thing for their community or the country. Now it would seem and especially for those who stand for parliament do it mainly out of self interest. If people want to stand for public office then that should be the only job that they have especially members of parliament. They are always complaining that they do not have enough time, yet they can find time to write newspaper articles or carry on their work as QC. If people stand for parliament this must be their full time job, if they want to carry on working in the city or at another profession then don't stand for parliament. Many people say that we need business people and entrepreneurs. Why would entrepreneurs want to stand, their sole object is to make money. Now there is nothing wrong with that but do these people stand because their sole object is firstly to improve their business contacts, or to add to their circle of acquaintances, before their commitment to the people. There is now a growing concern in certain areas of public life where the public want to know what these people earn. If these people who stood for public office were informed that they would have to give up all other outside connections, how many would bother to stand. We have government ministers that are trying to hide what their wealth is. Most people don't want to know this but they may well want to know what they earn in public life. Boris Johnson earns about £150,000 + as mayor of London but earns over £250,000 a year writing for a national paper. He may well declare what he earns and pays in tax. But all people who stand for public office should do so only when they decide that this is their sole job and can concentrate on that for the good of the peole that they say they want to represent. But in today's greedy world do the public believe that is why these people stand or is it as I believe for their own self monetary advancement.