Power. It depends on whom you can lord over. As a researcher, you are the overlord—of your study subjects, that is. If you wanted to, you could cause quite a lot of misery for the plants or animals you're studying. Sea slugs wriggling around in a petri dish—you could add one drop of something weird, and knock 'em out cold. All in the name of science.
Or, think of the power of discovery. You could be the first marine biologist on Earth to identify a previously unknown aquatic ant species that has been living in the depths of the nearly seven-mile-deep Mariana Trench in the Pacific Ocean.
Or, you could be the policy wonk biologist whose expert testimony on the importance of saving the rare and endangered snail darter fish and the ONLY reason that halted construction of a multi-million dollar dam on a river. You versus the developers. And you won.