Odds of Getting In
A lot of DPs are jockeying for a relatively small group of jobs. You have to prove yourself big time to stand out from the crowd. If you're not the next big thing, you're probably the next big bust.
Okay, the outlook really isn't so bleak. The number of jobs working behind the camera is expected to grow by eleven percent—faster than the average for all jobs—by 2024 (source).
The advent of new content delivery methods means the job of cinematography might expand to new media in the near future. This could mean lots more jobs...but it could also mean a thinning out of salaries for DPs not working in the aforementioned "big time."
If you hone your craft and network like crazy within the entertainment industry, odds are you'll get your shot at something having to do with camera and lighting work. From there, it's up to you to dazzle everyone with the results.