@tio
"It just pulls everything in to the singularity" - so you're saying it pulls stuff into that "point"? Then why are these black holes bigger, smaller, have a shape, a mass?
I'm no expert, but from what I understand, what they mean by the size is the event horizon. The event horizon is a boundary inside which light can no longer escape. So intuitively, this event horizon should expand when the mass increases because gravity increases with mass.