Uh – no. That’s not why they are bright. They pull in EVERYTHING, not just light. They are surrounded by a large disk of matter (called an accretion disk) that is slowly spiraling into the black hole. As it get closer to spiraling “down the drain”, it compresses and speeds up, which causes the matter to radiate and to shoot some matter off perpendicular to the maw (called a jet). It’s the jets and all that radiation the accretion disk throws off that makes a black hole bright. Ironically, black holes tend to be the brightest objects in the known universe, being easily easily visible trillions of light-years away.