The motivating factor behind the Bounty Hunters Guild (the in game group) is financial gain through a monopoly on the hunting and killing of criminals.
The motivating factor behind the Guild Core (the in game group) is financial gain through a monoply on the exploration of Nomad space.
See thw word monopoly there?
The Guild (like all Guilds) is owned by its members who are governed by a code that binds them. It is self-regulatory, maintains standards, makes demands from apprectnice before they can become journeymen and ultimately masters of their craft.