There are two types of Open Source users; those of us who understand and live by the ethos of FOSS, and users who just want to use a software that they don't have to pay for and don't care or understand the underlying ideas behind it.

That second group is the group who, no matter how many times they hear it explained to them, will refuse to believe that "free" doesn't necessarily mean "no-cost" and therefore develop an expectation of "free" and decry that you're not allowed to sell your software because it's open-source, and even asking for donations is forbidden, when in reality neither of those things is remotely true.

Far more important than anything is to change the perception of Open Source to something like value ware; If you value the use you get from the software, pay an amount that you feel is fair. If they can't afford it, that's okay, but if they can, then the expectation needs to be that they DO. Even just a few bucks.