What do you mean by all-in? 100% living from photography or being driven by nothing but photography? I make a living with photography (100%) but there are others things that drive me as well.
About being better at business, I guess that does apply to me as well. Even for the work I do, I regularly do things that are not being considered artistic or would have been my choice when I don't need to make a living from it. I see a lot of photographers that have to work in other areas because they refuse to do assignments that would compromise their 'artistic integrity'. They cannot make a living from photography alone. Is that what you mean with all-in?
You have a point - but as I found myself in the latter category of doing what I believed in, you are perhaps incorrect suggesting that such people cannot make a living from photography alone: I did.
It sure wasn't easy, but you can still do well if a market actually
exists for your preferred subject. Then, it becomes a matter of 'both feet in the water' - forget the boat or the shore and swim like hell. The thing is, if you really, really have such a strong desire, you will just do it anyway and no amount of planning, advice or other people's horror stories will make the slightest difference. In my own city, there were indeed other studios doing much more work and probably making much more money; most eventually dried up whilst I manged to hang on in, and even move abroad to a much better quality of life.
But, I suspect that most photographers have a limited period in their lives where it works out well, followed by decline brought about by changing market conditions and the fact that contacts move on into different lives too, and you don't always get taken along on the new ride.
If you don't have infinite belief in self, you get nowhere in this business.
Rob C