Mostly for finding information that for whatever reason can be difficult to find using search engines. For example, I've used ChatGPT to ask spoiler-free questions about plot points in books I'm reading, which has worked rather well. It hasn't spoiled me yet, but rather tells me that giving more information would be a spoiler.
Last time I tried to look something up on Google, carefully, I got a massive spoiler for the end of the entire book series.
I also use it for code-related questions at times, but very rarely, and mostly when using a language I'm not used to. Such as when I wrote an expect script for the first (and perhaps only) time recently.