I'm sorry if you consider it rude, but have you considered the people you're speaking to may have something better to do than to spend their time teaching you D

I'm sorry if you consider it rude, but have you considered the people you're speaking to may have something better to do than to spend their time teaching you Dutch, or alternatively, may just believe you actually want to discuss the subject at hand rather than practice your Dutch? If you want people to take the time and trouble to speak Dutch, consider asking them, preferably in a context without time constraints.