Characters are hard. There are thousands of them, with only loose auditory or semantic meaning. Learning to write and read Chinese is almost always going to involve rote memorization, hopefully using spaced repetition.

I've been studying Mandarin in a non-intensive but formal class for 6 years, speak a bit better than mark to Mark here and almost definitely with a larger vocabulary (though this could be 100% biased by the intimidation of a large fluent crowd in his case), and cannot even hope to read a simple Chinese novel or newspaper. I've heard anecdotally that doing so requires working knowledge of about 10,000 characters.