Is it a bad practice to quit a company only to begin as a consultant? [closed]

Question

Like the title says; is it a bad practice to quit a company after a few years, only to begin as a consultant for the same 'customer'?

I've been lucky enough to come in to a company in the oil business from the beginning, developing software for relatively new and unused technology. Long before I even got this job, I've wanted to start my own consulting firm. Is it morally wrong of me to quit my job after a few years, only to hire myself out as a 'specialist' or consultant on our systems?