A religious believer might call it destiny or could possibly say that it's based on the person's faith.
But one thing I believe is that how long one works does not guarantee how successful the person will be; rather, how smart the person works will determine the end result of that effort. as there is always a big difference between working smart and working hard.

So in the case of Mr. A working for the past 20 years without being able to make it out of poverty, it might be as a result of Mr. A just doing the Job just to get paid, and the payment is just being used to foot Mr. A's family's feeding expenses and needs, and there is nothing more than that needed by Mr. A.

And Mr. B happens to be doing the same work that Mr. A is doing but for a different purpose and with a different passion. Mr. B has passion for the job, and in fact, it might be part of what Mr. B considered to be hubby, and as a result of that, Mr. B puts more effort into being productive in the company, not just as a regular salary earner, but is sharing more value in terms of knowledge and ideas. You will see that Mr. B might likely have a greater chance of getting a promotion to a higher level where a salary increase will be necessary. and Mr. B might also be saving up his savings, which can in turn be invested in other things that could be of great profit in times to come, and as a result of that, the financial status of Mr. B will be considered higher than that of Mr. A.