We'll see, but I think the equivalent to people donating their own time to a traditional open source project would be people donating spare compute time for training, and nobody has figured out an effective way to do a Folding@home-style distributed version of ML training yet. Having to train open source models on big expensive compute clusters, and bid against commercial interests who also want to rent those clusters could be likened to having to pay everyone working on a traditional open source project full market rate for their time.