ML can be an useful skill for developer. Think of it as of linux / sysadmin skills, or as web design / UI skills - they are all quite different from software development, but many software devs have them. I think that applied ML slowly becomes a similar thing - an useful tool in a toolbelt.
It takes time to become really good at it, but basics are relatively easy to aquire. Libraries and learning resources are much better now than they used to be. You can totally learn how to apply ML using just scikit-learn tutorials. Coursera ML course gives a nice introduction. For deep learning check an awesome http://www.deeplearningbook.org/ and try to implement what you're reading about e.g. using https://github.com/Theano/Theano.
The world of AI is enormous indeed, tens of new worthwhile papers are published every day. Just reading them can be a full-time job, but you don't have to know all state-of-the-arts techniques to be dangerous. Over time it will become easier to read new papers, and you will start to realize how are ideas related. Often a paper provides just a small tweak for a known algorithm, or combines existing "building blocks" in a new way.
As with all skills, it takes time to become good at it, but there is nothing to be scared of. Keep learning, do something practical every week. If you don't have problems at hand to solve using ML, register at kaggle.com. There is more to learn than e.g. in devops, but everyone can do it.