Appearance of your results is everything ... besides your bottom line.
Real estate agents are not at all put off by the appearance of a Phantom, those I've worked with are more than impressed with the technology.
We might think they are toys but no agent I've dealt with treats them like that.
All they need are small pics for online listings, an A4 size pic for the window display and maybe an A3+ shot for a signboard.
They have no need for ultra results and certainly don't want to pay for them.
If you get a $20K outfit and go looking for work in real estate, you will have a hard time ever paying for it.
In real estate you need a compact machine that is quick to deploy and can fit in tight spaces when required and the Phantom is perfect ... the Mavic would probably be even better..
Agree Phantom is great for real estate, $20k is too much of a startup investment in a high end piece of gear when you're starting out. An Inspire is overkill until you are an expert pilot and deserve one through earning it with a successful business (or if you're flying one for a production company, etc.). 99% of real estate imagery is for digital listings, websites, MLS, etc. An inspire is a feature filmmaking quality level UAS.
To add:
Results only get you so far. There are plenty of crappy photographers/videographers (and other creatives) out there making a living, some making a killing. Your
network and business acumen is your net worth. I believe in perfecting your craft, always evolving, getting better, and producing high quality work, though in your career - networking and business is far more important than your gear and your skills 1000 times over.
Personally I'm bringing aerial imagery into my existing high end commercial photography business with a
Phantom 4 Pro, so I do agree to aim for the top of the market (the low end won't help you make a living, the middle is crowded). On your way there your networking and business building skills will far outshine your imagery. Learn the hustle, build your skills along the way.
Private real estate is currently the most crowded drone market because it's the most obvious and easiest to get into (the barrier to entry is a $1000 drone, a $150 FAA license, and some hustle). And yes there are many industries other than real estate to make a living with these things!