> Similar farms can be built on Mars.

I'm an Elon fanboi but please let's start with desertified populated regions first so we have time to build a Mars colony without having to deal with civil wars

Both objectives can be worked on at the same time. I don't really like that argument. We could say "let's end hunger first then focus on computer games, or beer, or vacations, etc". Ending world hunger is way more important than those things but you can't expect we stop doing them to focus on something that is already being addressed but is very complex.

You can't solve world hunger on the supply side. There will always be more hunger afterwards.

I know but that's not my point.