Oh yeah almond milk REALLY is not an eco friendly option. Your buddy is right on that. It doesn’t help that Almonds are usually grown in countries that are poorer, exploiting them and draining them (even more) of their water supply without paying them.
There’s an entire metaphorical water mafia going on that effectively steals water from third world countries while using underpaid (and sometimes even slave) labor. Almonds are one of the things said water is used for.
Even from an animal rights perspective that’s messed up because of human mistreatment.