What I mean is that having a runway where your union members can do literally nothing for 500 years and continue to get paid would suggest there is a monumental amount of cash sitting in a bank. I agree that unions need a rainy day fund, but this seems egregious. If they had said 10 or 20 years, that would make more sense to me.
It's likely that not every union member is striking, it is probably a sectoral union, e.g. the Swedish Dockworkers Union. There is still a lot of other dock-work to do besides unload Teslas, one would assume. So the union has 500 years of funds but that's for some small fraction of the workers.