Depends. Some women cannot have enough milk production, some have over production. It’s a bit of a gamble most of the times. In countries like Brazil there is a sort of system where is possible to donate milk in case of over production, and in case you don’t have or not enough, you can have some of it (not sure about the details, but for me this sounds great).
As for people saying formula is better than breastmilk, believe or not, Nestlé is to blame for this. Back in the day they touted that all over the place, and at some point, they got penalties for saying such bs. The fun part? They are using the EXACT same tactics on some under developed countries so they can sell more. Quite frankly, Nestlé is really up there on companies to despise ( Exxon is possibly the top one, but Nestlé is not really that behind)
What a fantastic website not to visit