when is it time to stop breastfeeding?

my baby is about to be 6 months old — people keep telling me it’s almost time to stop but I don’t understand why? I wanted to breastfeed for at least a year — and if I choose to do any longer after that I could always pump and give him bottles if it’s not appropriate after 1 year…I’m just confused because I was under the impression that the benefits are good for them at least for the first couple years. I keep seeing parents give their babies cows milk after a year? why give cows milk when I can give him my own milk? just want to be clear that I am not at all judging anyone! this is just my first baby and so I’m just trying to make sense of everything