Martin Paul Eve on scholarly associations:

But the truth of the matter is that Learned Societies are funded by academic library budgets. If they rely on a subscription model, they are also reliant on excluding people who cannot pay, for the claimed good of the Society.

Eve throws the problem—how to fund societies outside the subscription system—back at the societies themselves:

So what is the answer? I do not know. But if I were a Learned Society, right now, I would be urgently experimenting with zero-embargo green OA as a stop-gap measure. I would also be considering the transition strategy to a consortial model that I mentioned above. I would also be firming up every single argument that could justify the Society’s existence. Because it seems clear to me that the era of bundled subsidies is slowly melting into air.