Odds of Getting In
The music industry is humming along quite nicely, despite the loss of album sales as a result of music streaming and pirating services. The musicians keep making money because bands are actually touring more than they used to—so there's greater demand for roadies to tag along on all those tours.
That being said, lots and lots of people would love to be touring with the band. Part of making it will be spotting the right moment or meeting the right person. You won't find many ads for roadies in the Classifieds section of the newspaper. Most roadies end up in the profession because they were already a part of the music scene or were friends with someone in the band.
Because there's no set formula to get you a gig as a roadie, you'll just have to make connections where you can and express your interest in joining a tour if you feel like you've met a person who can make that happen. If you can sell yourself as somebody who'll be hard-working, helpful, and generally easygoing, you should be able to find your way onto a tour bus.