I wonder when the demand side for decentralised GPU marketplaces will kick in. Will probably require heavy BD + Marketing + technical breakthroughs on distributed computing

There's no lack of supply of consumer GPUs rn. 

IO.net has 300K+ GPUs on its network.

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very good point, i've been reflecting on an adjacent question; 

what will be the key differentiator for the most successful distributed compute platform(s) (feels like new ones pop up every week). 

balanced supply/demand is likely one key.