I have boarded horses in the past. It really isn't a good way to make money, because the extra insurance you should carry for a boarding horse (versus one you own) is fairly expensive. It covers you in case someone (a boarder) gets hurt on your property and/or horses get off your property and cause damage. Now that I am not boarding horses, I don't carry an equine policy specifically, but have a large umbrella policy. However, there is still an inherent risk to having horses because they can and do get out, and if they do...can be trouble.
That said, I did find boarding as a way to offset my own horse expenses...so while I didn't *make* money, I was able to slightly decrease the monthly expenses that I was spending anyway, because I made a little bit of money. (As I said, the insurance part sort of tips the scale on that one, but in theory, it might help.)
I do agree that people are not going to be very willing to want to board with you if you have no experience caring for horses. Even people that have ridden for years in a lesson program may not know how to recognize a sick horse, or know what to do in an emergency.
Hard to say the best way to jump in -- I just went ahead an bought a farm and bought a horse (had taken a few years of lessons) and a pony. I don't think it's impossible to imagine caring for horses even with only a little experience -- IF you have good support systems -- vet, farrier, friends, trainers, AND you have the money (and are willing) to pay them. I was lucky to find a lot of people nearby and willing to help so it has worked pretty well for me. And, I read everything about horses and horse care I could find to help me learn faster.
In the future, I might consider boarding again; but it would be in very specific situations -- e.g. retirement care or long term layup, for example. I would want to minimize the number of other people (boarders) that could make my life problematic, leave gates open, or just annoy me.
