With all the hype about drones recently in the past 1-2 years and the fact that RTF (Ready To Fly) drones are getting more advanced and easy to fly, almost anyone could buy a "drone" off the shelf and call themselves an aerial photographer or drone operator today.
In the past, taking photographs or videos from radio controlled aircraft were used to be reserved for people who only have the knowledge & know about electrical engineering or RC modelling.
"Professional Aerial Photography requires more than having a Photographic Eye"
Why do I say that? It is because an aerial photography platform is a highly sophisticated piece of equipment. Failure to understand how it functions or works will result in serious accidents or damages. It is not just all about getting the correct angle or pictures & having the creative eye. I agree that is an important aspect, but the point that I want to emphasize here is that a true professional aerial photographer should know how his aerial platform works extensively, from how it was built to how it functions in every different condition.
"To fly an aerial drone platform professionally & to understand it thoroughly requires years of experience"
Before RTF (Ready To Fly) drones were the norm, I was flying radio controlled airplanes & helicopters as a hobby. Subsequently, I built my own DIY drone platforms for aerial photography. Over the past few years, I have hand-built almost 4 - 5 different drones. Initially, it was a steep learning curve for me, but soon I got the hang of it which took about months of self learning from other experienced builders over the internet & from a buddy of mine who is an engineer specializing in building drones & microchips.
"A sense of accomplishment & taste of success"
The moment you complete building your own drone, fine tune it and get awesome aerial footage from flying, it will give you an overwhelming sense of accomplishment and happiness. I dare to say that this is something you will never possibly get when you fly an out-of-the-box-ready-to-fly drone.
Check out the drone aerial video i made some time back with my DIY drone below. I customized almost every flight characteristic of my flying rig to my preference. Something you can only do with a DIY drone.