Is almond milk an improvement with regards to environmental impact, though? Almonds are a very resource-intensive crop, and in my experience there’s a lot of waste involved when making almond milk.
It has ~20% of the protein and fat content of regular whole milk, so at the very minimum it has to be 5x environmentally friendly.
In fact it is so nutritionally empty, that it is more fitting to compare it to slightly sugared water, and see if it beats that on environmental record.
I think more people drink milk purely out of habit/pleasure.