With a job you can invest little bit every month in bitcoin and if bitcoin continues to steadily rise every month by 10% or something then you would get 10% profit every month from what you have in and put in but ofcourse it wont rise steadily like that but if you count how it rises over time then its almost the same.
It's good if you have that kind of mentality, doing it on a monthly basis requires enough dedication and discipline, you have to follow the most effective way for saving money which is income less savings then your expenses. That's the formula of the rich and successful people, so it's a challenge for us.