> if it was zero sum - you earning money would mean somebody losing it

Earning money means somebody loosing it. It is only possible to earn w/o somebody loosing by either narrowing the definition of somebody, or limit the time frame in which the process is occurring.

For example, most of the animals are not considered somebody, that's why their loss of habitat, is not considered somebody loosing money.

I think in economics these are called externalities. It's not that they don't have a cost, it's just that we prefer to ignore it, because there's nobody to complaint about it,