I breed/train/sell miniature shetland ponies - not falabellas, but similar in size.
Anyone who has any small pony needs to bear in mind that for all their size, they are still a horse. And I don't know about falabellas & other miniature horses, but my shetlands all believe firmly that they are about 16hh!!!
Any small pony requires exactly the same care as a bigger horse - vaccinations, worming, safe fencing & grazing, handling, feeding, etc. Some things are cheaper (they eat less hay, feed, wormer), but other things will cost the same (farrier, vet, livery) as if they were a larger horse.
They have the same requirements as a bigger horse, like company. Some, rare, horses are happy alone, but as a species, they are a herd animal, and should be kept always with company.
Shetlands in particular have a very bad reputation. I have 22 of them currently, including a colt & a stallion. My four year old daughter can lead even the colt & the stallion. She is safe to be out in the field with them, or in the 'big' field with 18 of them. And that's as it should be.
The thing is, I have a big horse background, and I treat my shetlands like they are big horses. I expect the same manners & level of handling / training. As a result, mine are all lovely to be around, and generally good to do. And this is the key to shetlands - treat them like a big horse, and you'll be fine. Treat them like a pet or a dog or a baby, and their intelligent little brains will start working overtime, and they'll give you a major run for your money!
It's also worth bearing in mind how bright they are. They do need attention, and to be doing something. They can be walked inhand, ridden, driven, long reined, lunged, freeschooled, etc. And they are better for doing so.
The problem wiht shetlands is that if you give them an inch, before you know it, they've galloped a mile! ;)