We have decades of real world experience which shows this is not true. People buy things they could otherwise get for free with a bit of work all the time.

you aren't getting a company to build baldurs gate 3 and hope they recoup the costs from ko-fi donations.

real world experience is that most companies do not offer their software for free, and open source developers either have to get sponsored or have to constantly solicit donations.

donations do not typically cover multi-million dollar, multi-year development cycles.