It seems it isn't that simple. It looks like wild plant conservation lacks funds, and that the operation of saving a plant from extinction is hard. To the thief it doesn't matter if he sells the last lily on the planet for $10k. That's $10k he wouldn't otherwise have. And he has no particular interest in selling to a conservationist. It doesn't matter to him if the plant dies.

However, in general, we care. We want to preserve these plants for their own sake. But thieves don't. There is a strong feedback loop: the fewer of a plant there is, the better the gain from stealing. That's bad for us, since we want more plants, not fewer.