Here's why:

* Galaxies are enormous: Galaxies are vast collections of stars, gas, dust, and dark matter, spanning hundreds of thousands, even millions of light-years across.

* Black holes vary in size: While supermassive black holes reside at the center of most galaxies, they are still significantly smaller than the galaxies themselves.

* The Milky Way's central black hole, Sagittarius A*, is about 4 million times the mass of our sun, but its diameter is only about 15 million kilometers.

* The largest known supermassive black hole, TON 618, has a diameter of about 130 billion kilometers, still dwarfed by the size of a galaxy.

Think of it this way: Imagine a basketball (the black hole) in the middle of a football stadium (the galaxy). The basketball is massive, but it's still incredibly small compared to the size of the whole stadium.