Almost every investor is either directly or indirectly invested in companies that provide dividends.
As for other examples, housing is another popular one.
As for other examples, housing is another popular one.
Housing market is same zero sum as OP described determined by investments in real estate instead of other assets
Any other examples?
Over the long term effectively 100% of all stock market returns comes from either dividends (and buybacks) or the companies increasing ability to pay dividends (through earnings growth).
I'm not sure why you think having a place to live ( or to rent to someone else) is not productive... mind explaining?