probability

Quantifiable likelihood (chance) of the occurrence of an event expressed as odds, or a fraction of 1. Probability is estimated usually through repeated random sampling, and is represented numerically as between 0 (impossibility) and 1 (certainty).

Don't think about a potential venture just in terms of the time commitment, the cost, the probability of success etc. but also think about whether you will have fun doing it. You can't do something for too long exceptionally well without having fun in the process because if you don't enjoy it, you won't be intrinsically inclined to go the extra mile.