I think that every student or job/business person think like that at a juncture of time in his life, specially when he doesn't get desired results. So it is normal part of life and there is nothing to regreat about.
I assume that less than a 1 percent of total population of a country gets a chance to go through the professional courses like CA, CS etc.
Judge yourself by looking at the both aspects of coin in light of your interest and efforts. God never bias or injustice, may be we misunderstood him or we want more than we deserve or make efforts.
I remember a line, which i just read again- Small houses built fast but great buidings like Tajmahal take time.
So dont regret about past, be hopeful about future and enjoy your present.