Tom ... You might want to look at this from the other way round ... why have professional researchers stopped being professional researchers ?
I spent about 10 years doing this work. I offered research in a single English county and got to know the RO very well. I advertised and a steady stream of work came in but whilst there was a profit to be made, it rarely amounted to much.
Apart from overheads like advertising, materials, photography permits and travel,
time is the biggest problem. No doubt you enjoy ferreting out all sorts of info for yourself, but consider the time it takes you, and then consider the time it would take you to write it all up in a professional report, and then consider the time it would take to draw up a tree whether by hand or by computer.
It might be worth going through an exercise like that; work out a quote for it first, then do the work and see how accurate your quote was ... and then consider whether a client would pay that amount for your work.
The hardest thing I found was charging a client for three hours work with no results whatsoever.
I stopped working for none of the reasons above. I stopped because I found that more and more folk were doing there own research online (consider the 23,000 & 11,000 learners for the two FutureLearn Genealogy courses). I eventually worked out that I was being asked to do all the 'brick wall' work, and that meant a lot of disappointed clients, no follow-up work and no word-of-mouth work.
Please don't think I'm just a grumpy old man ... try it for yourself, enjoy it, but don't expect it to pay the household bills.
