Most muggles don't have a clue about how much magic is working around them. On their jobs, on their marriages, all around them professionals or dabblers are working, creating circumstances that will change their life. The muggles that are slightly aware of that make an effort to avoid being collateral damage. Against an unjust boss, a hungry ghost, an envious person wanting to wreck their marriage, or just plain old bad luck.
They hire people like me to protect their jobs and to keep their paths open. That is good for them and for professionals all over the world.
And the good professional cleans the muggles path, remove curses, blesses them, and if need be, kicks the client's ass to make sure that they have a chance.
But there is always an idiot, that instead of working against the workings of others decides to make a name for him/herself by attacking the other professionals. That is stupid because quite often the workings will keep damaging their clients even if he/she is sucessefull in wipping out the competition. It also attracts unwanted attention. We are a paranoid breed and the demise of one of us makes all others smell the blood. Besides most have friends/companions/students/partners that in al probability will act against the attacker. The result may be one of the endless and petty witch wars that plague our existence.
My advice ? Don't attack another professional unless you have a damn good reason for it. And if you do, gather as much help as possible and make sure that he/she is dealt in such a way that others don't want to risk attacking you.