I will say that people are using spaCy for free because that is what we asked them to do. I chose to make the library free and open-source when I first released it because I had the idea that I would be able to make that work out for me, if I could make this thing that would be useful to people and if they could be convinced to adopt it. And in order to convince people to adopt it, we've been telling people that spaCy will stay free and that we'll continue to work on it. So everything's going to plan here. Even if things weren't working out well for us (and they are), the fault would be entirely ours. I don't think we'd have any right to suddenly say, "Oh none of you jerks are paying, how unfair".
(For the record, we make money from sales of our annotation tool, Prodigy: https://prodi.gy . If you're reading this and you like spaCy, check it out ;)