Maize ends up being one of the most economically efficient and calorically dense crops to grow. If you have very little money to invest in your land, it's definitely one of your best choices. We're trying to get farmers a bit more capital access to be able to move to more productive systems, but if you don't have an extra 50$ for fertilizer, you definitely are going to struggle to switch to potatoes.
Yes, but it's often less resilient to variations in weather than other crops that are native in the region. So it's great until you get a drought and then you end up with a famine.