You buy “stuff”1 everyday. Some are essential, but many others that you probably don’t need. In any case, imagine two scenarios.
You go to a store to buy and like the look and feel of it. You pick it up and head out of the store. No payment, no receipt, no credit card swipe. Then one day, when you have used it enough and feel that it was worth it, you pay for it, and you pay what you think it was worth. No price tag, no time limits, no collection calls, just your moral obligation.
You are enticed, cajoled, convinced or fooled into buying it. Pay for it upfront with limited warranty on the product, no guarantee of satisfaction and very few options of getting your money back.
Which one would you chose? Obviously scenario 1, isn’t it?
Not just because it is free until you decide to pay for it, but also because YOU are always in control.
Does it sound too idealistic? Are there even such products and services?
Yes, and many that you are likely using quite regularly too but may not even be aware of it.
Open source software is modeled exactly on the first scenario. Furthermore, many of these are ad-free. Do you rely on Wikipedia, or use Mozilla Firefox or prefer Linux (more accurately GNU/Linux) or any of the thousands of “free” software out there?
Such ecosystems can only exist and sustain with voluntary collective contributions. There are many ways to participate but financial contribution is important. The ball is in your court. Participate in any way possible and fulfill your shared responsibility.