People who paid for your software don't really have a right to lord you around. You can chose to be accommodating because they are your customers but you hold approximately as much if not more weight in the relationship. They need your work. It's not so much special treatment as it is commissioned work.
People who don't pay are often not really invested. The relationship between more work means more costs doesn't exist for them. That can make them quite a pain in my experience.
> People who paid for your software don't really have a right to lord you around.
Of course I realize that, rationally, but:
* They might feel highly entitled because they paid.
* I feel more anxious to satisfy than I should probably be feeling. Perhaps even guilty for having taken money. I realize that is not a rational frame of mind to be in; it would probably change if that happened frequently. I am used to two things: There is my voluntary work, which I share freely and without expecting money; and there is my 'job' where I have to bow my head to management and do not get to pursue the work as I see fit, and I devote most of my time to - but I get paid (which also kind of happens in the background, i.e. I never see the person who actually pays me). Selling a product or a service is a weird third kind of experience which I'm not used to.
You think you need to bow your head to management in your job which, while you technically are under their authority in some ways, isn't really how I advise you to frame your relationship with your work. You are here to bring value and your manager is there to help you/ensure you do that. Still that's a framework not a rigid guiding stick. You need to learn how to manage/bend your manager if you want to thrive in the corporate world.
Same with customers. They hire you because they need your expertise. It's a dance not a tether and you need to be two to tango.
It seems to me you are not putting enough value in what you bring to the table. It's easier to say than it is to feel it and believe it but I guess it's never a bad thing to tell someone.
I'm probably projecting the idea I have of myself here but if someone says
> every exchange is about what's best for humanity and the public in general
it means that they are the kind of individual who deeply care for things to work, relationships to be good and fruitful and thus if they made someone pay for something, they think they must listen to them and comply their requests, because well, they are a paying customer and the customer is always right, they gave me their money etc etc
You can care about the work and your customer will still setting healthy boundaries and accepting that wanting to do good work for them doesn't mean you are beside them.
Business is fundamentally about partnership, transactional and moneyed partnerships, but partnership still. It's best when both suppliers and customers are aware of that and like any partnership, it structured and can be stopped by both partners. You don't technically owe them more than what's in the contract and that puts a hard stop which is easy to identify if needed.
Legally speaking, accepting payment makes it very clear that there is a contract under which you have obligations, both explicitly spelled out and implied.
People who don't pay are often not really invested. The relationship between more work means more costs doesn't exist for them. That can make them quite a pain in my experience.