If people don't pay for FOSS, how do you expect developers who develop FOSS to feed their families?
The "free" in "Free and Open Source Software" is free as in speech, not free as in beer. We'd like to think that decision to charge or not charge for the product is orthogonal to the decision to make the source code available. In practice there is some interrelation.
Do it as hobby in their free time? Maybe work in some other field producing actual physical things during day and then in evenings spend hour or two tinkering with free software? Just like any hobbying artist?
The "free" in "Free and Open Source Software" is free as in speech, not free as in beer. We'd like to think that decision to charge or not charge for the product is orthogonal to the decision to make the source code available. In practice there is some interrelation.
But FOSS was never "you can't charge for it."