The first are researchers at small liberal arts colleges. While these institutions specialize in teaching, their faculty are often pressured to publish, but not given a lot of funding or time to write grants. If I were teaching at a small liberal arts college, I'd seriously consider this as an alternate funding model.
The second group consists of people who do research that is really interesting to a small subset of individuals, but not particularly well funded. My lab in graduate school specialized in aging research. While I was there the funding situation was brutal, and somewhere around ninety percent of the grants in our area were being rejected. There's no way a project like Microryza could have covered the costs of the entire lab, but a direct appeal to the singularity-crowd might have brought in enough to help keep things working smoothly while times were tough.