If your orcas only last a month, you are pretty dumb.
Because you are dumb ? Easy guess.
YOUR whole argument does not make sense at all.
CCP does not decide how much ISK you make from trading, AND they improved the orca, so your complain is just that orca mining became less worth than barge mining, WHICH WAS INTENDED IN THE FIRST PLACE. You need to be VERY dumb to not realize that.
YES it was the goal, that orca are less interesting, mining wise, than barges and exhumers. So YES when the total income from mining is stable, then its share of income becomes lower. AS EXPECTED. And even though the orcas were buffed.
Do you even play the game ?