I think it's fair that if you've purchased specialized mining equipment, you expect the ROI you were promised. Doesn't seem strange.
> Ethereum functions on proof-of-work and needs some people to sell their compute time and electricity
So compensation for work. If not 'workers', you could call them 'investors', or perhaps 'sole traders', or 'merchants', not sure what the best analogy would be. To be fair, I don't necessarily put them in the same class as people making socks in a sweat shop on slave wage. The down-trodden Ethereum miner is not someone I lose sleep about.