Of course. It's simple. Spend fifteen or 20 years learning everything you can about locating people, bounty hunting, repo work, insurance law and adjusting, product liability, rules of evidence, security-perimeter and executive-surveillance and technical surveillance,arson, photography, surreptitiously recording, eavesdropping devices,TSCM (technical security counter measures), medicine, forensic medicine, drugs, criminal and civil law, penal measures, accounting-forensic accounting would also be a plus-executive protection, management software, weapons, interviewing and interrogation, and litigation. Throw in a couple of divorces, and if you're married, be prepared for one. Simple.
A lot of people believe that they have the skills for this work and many do and can develop them easily enough. But the thing they overlook is the nitty-gritty, day-to-day grinding out results. PI work is a lot of things, but firstly, it's a business. And many aspects are routine to a numbing degree. It's like any profession; anything worth doing will likely take a lifetime to master. Like any endeavor, it's not something one should take up lightly.