The reason Sam made a deal with Arkiv is simple. He wanted to go after the big fish faster so that they could grow faster.
As for why the small fish has to be completely eaten by then, it is very simple.
The big fish are limited in number compared to the small fish and they are way too strong. Except for Sam who has advantage of numbers in his favor, no one else would be able to directly clash with the organization on their own in a short span of time which would make this competition, span over decades.
So, the only other way is for players to attack an organization simultaneously. The overlap is bound to happen as they progressed and once that happens it would be easy for them to deal with them.
Sam wants that chaos to be created faster, so that he could learn and grow faster. He needs the experience and the resources more than anyone else.
