Millions of people around the world play poker. Of those, only a few thousand are professional. The remainder would probably like to be. They sincerely like the game, yet they don't have a passion for it. For them, poker remains simply a hobby.
This is the case with a good many aspiring emcees. They love rap, they have favorite rappers, know all the words to their songs, but in reality, hip hop is simply their hobby – enjoyable entertainment. Even so, there is nothing wrong with this.
The idea of "not taking rap seriously" does not necessarily refer to the art of rhyme, but instead to rap as a career or business opportunity. So while Master P may not rack his brain trying to craft the most amazing rhyme, he does seriously analyze marketing strategies, distribution outlets, promotional events, etc... all part of the rap game.
Some common signs that a new rapper is stuck in this rut are that they try to come up with good ideas, have writer's block, and stop. Or come up with a few bars or verses, think they're no good, get upset, give up for a while, and pick the pen up again in a couple of days or weeks. For these people rap is a hobby.
Rap is made a hobby by others because they are afraid to fail at it. Remember this! And it applies to everything you do. Success is achieved only after many failures. If you can't handle failure, you're not ready for success.
The Hobby Factor - Solution:
Make rap a priority, set some time aside to dedicate to it. This doesn't mean "forget all your other responsibilities, but do write every day. Writing every day sounds very simple, agreed, but it is rarely practiced. The practice becomes understood to be "write a hot verse/song every day" which it is not.
"Write every day" simply means that. Write down your freestyles, a poem, the opening page of a short story, ideas for a song, literally anything! You'll be amazed at how drastically this will speed up your learning curve.
Another good idea is to change your entire frame of mind. Let's say you're living at home with your parents. Things are pretty straight, you're not starving. You plan on being a mechanical engineer. What then is motivating you to improve your raps?
Now let's say you got your girlfriend pregnant, are living partially on the streets, working two jobs to eek out a living and you see rap as your way out. Well now you've got some motivation?
The point is not that you need to be in any particular circumstance to be a good rapper, but that if your situation isn't motivating you, you need to create that motivation by some other means.
Rap with a hunger like you literally need it to eat! Don't treat it like a pastime. Whether you end up becoming a successful musician or not, the time you dedicated is never wasted. Good rap skills and song writing skills are amazingly beneficial to developing a good ability to express yourself in any field.