Breast feeding

So my friend was able to breast feed for maybe 6 months but she knew she wouldn't be able to long at 2 months so she started switching it up by giving a bottle of regular milk, no formula, and then breast feeding, just to get his body used to it, because she doesn't like formula, no offense to anyone but she just felt she didn't like formula because she felt babies were healthier and happier on breast milk vs that.. I understand not all women can but in this particular case what's your thoughts on switching to regular milk afterwards.. I know Drs consider that neglect, but her counterargument was "what did our parents have? Milk.. And they're fine" and I agree, but I don't really know abt the milk thing, I'm kinda 50/50.. I guess  wondering what everyone's opinion is.