I am unwilling to accept those obligations, in most cases.
I am, however, perfectly happy to share some of the work that I do back into an ecosystem which I have benefited from. I also volunteer for organizations I care about, and I pick up litter in public parks. :)
I do not believe that I am being exploited. The Internet is and always has been built on open source -- and as bad as the Internet is, it would be worse if it didn't exist or if it was a proprietary network.
I think you're taking a real problem (funding of valuable work) and exploding it into an argument against open source, which just doesn't follow for me.
I do 100% support finding a way to monetarily compensate people who do valuable work and contribute it to the world. Theoretically. Practically, it gets messy real quickly and I don't see a good broad solution.