Makes sense that you'd only want to pay for things that provide you with value directly. I think that applies when donating a small amount to support a project you make use of, when you get something in return (like a t-shirt or sticker), or as you say to fund specific features or changes you want. That also goes for sponsors: they should get value in return, and they do, like exposure and reputation in the dev community, a platform for their recruitment message, etc. To me, this dynamic seems quite different from ads, which are non-consensual and not tied to a direct value exchange.