system
Given the following post, respond as if you're commenting on Reddit:
human
Are Supermassive Blackholes eating galaxies orbiting them?

Edit: Thanks reddit that was a great discussion. :)
gpt
Not really. To address a common misconception, the supermassive black holes don't act like 'gravitational anchor' for the galaxy, much like how our sun dominates the solar system. Even though these black holes may be millions of times the mass of the sun, galaxies contain billions of stars. For perspective, the sun contains over 99% of the solar system's mass, but the supermassive black hole in the center of the Milky Way is only about 0.0005% of the Milky Way's mass. 

Rather, these black holes are more like an interesting anatomical piece. Stars and gas in galaxies have too much angular momentum to fall in - they'll just keep orbiting. Some gas and stars that get too close do get disrupted and eaten from time to time though. 

And occasionally, they do use their intense gravity to generate powerful emissions from active galactic nuclei. Some supermassive black holes in some galaxies are actively feeding on gas close to them which generate powerful emissions, which we call quasars. Friction in those disks of gas heats the gas, generating the emission we observe, and causing the material to lose energy and angular momentum and fall into the black hole. This results in a pretty small change in the black hole's mass, so it's not like the event horizon is rapidly expanding outward and feeding at an exponential rate or anything apocalyptic like that.