Like Sean said, setting up a home lab is the best way to play and learn. If you screw things up, you won't lose any corporate data and you can just start over.

There's a good book on troubleshooting available for download from this site at http://www.sqlservercentral.com/articles/books/76296/. There are stairway series on this site that explain a lot of things from start to finish. Perry Whittle's series on AlwaysOn at http://www.sqlservercentral.com/stairway/112556/ does an excellent job of explaining clustering and I'd recommend it to anyone.

Like Alan said, DBAs are in demand. Good ones are very in demand. The job description is, so it seems, perpetually in flux. There's never a shortage of things to learn. Continual learning is just a part of the job.