> when you give away your work and time for free
> I gave away ... the reward was
You're expecting a reward for your charitable work. A grocer faces its own hardship too (the late night alcoholic who trashes one of your aisle), but it's made bearable by the flow of income this provides.
Get paid. Like seriously. At least make the companies pay. You seem to be in exceptionnally successful with your project and well connected, why not try to start a kind of open-source consortium with other maintainers and companies to try to get some momentum into normalizing the fact companies should pay for the libraries they use. Surely, any company can throw 10k a year into open source projects, there must be a solution that doesn't leave people like you disgruntled.
Civil behavior and thanks isn't a reward. It's the lowest of baselines for being human.