In SOME areas and in SOME economies you could possibly get-by as Aerial Only but that's the exception not the rule.
In addition to what
@Ty Pilot said (and I agree with the vast majority of it) look at it from a Realtor's point of view.... they are wide open with no time to spare... it's your job to SAVE them TIME and help them Make More $$. By ONLY offering aerials this means IF they call you they also have to call someone else (or go themself) to take the other pictures. This is multiple phone calls, multiple scheduling the home, and multiple payments.
We started doing this years ago when I was literally the only LEGAL Commercial UAS operator in the state of NC. At that time I was in HOT demand but today "Aerials Only" is a very tough sell. I'd say out of my last 100 shoots we did Aerials Only only about 5x.
1x the Photographer's drone had been crashed
2x the photographer didn't feel "comfortable" shooting with her drone because it was a very "technical" shoot (flying through wires, trees etc)
2x It was LAND ONLY and that's something we have a very strong reputation for doing and doing well.
In todays HOT climate many REA are literally taking Cell Phone pics and selling huge listings with just a simple pic and maybe a GIS Screen Shot.... no need to spend more time, money, and effort with it sells with minimal of efforts.
Unfortunately I know of several individuals who started with similar questions like yours but they went ahead and made that leap.... I'd estimate less than 10% of them we in business more than a few months at best. an Aerial Only venture would be a very bad BAD idea. A few years ago this was a totally different answer but today it's not a good plan.
If you want to start a business do it the right way. Learn about Running A Business (it's a lot of work and a LOT of time) and how to set it up properly from the beginning. Like a house, a Business needs a strong and sufficient foundation for long-term success. Take short cuts and you'll most likely fail short term. Take some business courses, learn how to and develop a strong and robust Business Plan and you'll be well on your to to success. These don't guarantee success but they definitely make a profound difference.
I hate to pop anyone's bubble but I think you need and deserve to hear some facts without any emotion attached to help you make a more informed and intelligent decision.
Good luck