Ask HN: AI/ML vs. BigData

I am currently working (mostly) across the stack building out applications (web/native/server). I've recently been think of moving to either AI/ML or Big Data.

I am personally interested in ML, but I find it difficult to see what kind of impact I could have working in ML. The impact of working in/around Big Data seems to be a lot more direct.

Which of these would be the wiser choice? Has anybody here made the jump from full stack engineering to either of these fields? If yes, how did you go about convincing your current employer to let you switch?