Odds of Getting In
You start trying to make it big as a singer. We'll buy a lottery ticket. Let's see who strikes it rich first. Our money's on us.
The sad part is that not only are your odds of becoming a huge success slim...your odds of even making a living at it are less than promising. Few singers/musicians are able to support themselves solely with their art. Meaning you're probably going to have get one of those "job" things you were trying to avoid in the first place by becoming a musician.
In many ways it's a crapshoot, but if you're super-talented, charismatic, and driven, your odds go up. From 0.000001% to about 0.000002%.