Addiction may be a harsh term for fishing but I don't think obsession is. Spending $ on fishing that one can't afford can be as harmful as any addiction, does it make a difference what you spend your money on to leave you broke, the rent is still due. An addiction or obsession that takes you away far too much from your family can be very unhealthy as well.
To paraphrase what is said on Francho's signature line,,,,,,,,,,,,,most anything in moderation is ok, being excessive isn't..