When you work as a creative freelancer, sometimes... ugh... more often than not... you will get people (a.k.a. asshats) who think it’s cool for you to do free work. This can get a bit tricky because sometimes people need to be educated that you actually do get paid to do what you do creatively.
Don’t take it personally. We need to train our clients on how to communicate with us especially when it comes to being paid for what we do. So take it as an initiative to make the world a better place and inform the ones who need it on how you and the rest of the creative community like to be treated, talked to, and paid.