By sharing in losses I mean losing money in absolute terms, that's what happens to owners. Owners don't just make less money in bad times, they lose money. Workers may lose money relative to what they think they would make otherwise, but they still make money.

Accepting the risk of losses is why owners have a legitimate claim to the profits. Workers take a guaranteed paycheck which shelters them from losses in bad years and forfeits their claim to profits in good.