We produce enough food, now, to feed every human being on this planet. In fact we make 17% more food per person today then we did 30 years ago, even with the population increasing over that time period. [1]
Ending hunger is an achievable goal.
>I don't think it is smart to stop everything else until we get there
Again, no one is saying we "stop everything else until we get there."
Production is just a minor part of the problem. Yes, there's an excess of food/water in one places and shortage in others, but how will you get these (often short shelf life) products from former to the latter efficiently? Who will pay for this? It's like saying that we have unlimited energy, because Sun produces vastly more than we need -- yes, technically that's correct, but it takes a hell lot of effort and resources while it reaches you wall socket.
It sounds a bit like it. Because also the main problem with this thought is, it requires a different distribution mechanism. Socialism for example. And or managed economy. Because today food gets produced the capitalistic way. To make money. Not a charity. Poor people don't have money.
So if there is a charity to buy enough food and able to distribute it to everone ... ok. But many tried, and you could argue it disrupted local food economy (charities bringing in free food, nobody bought from the local farmers anymore, they went out of buisness, simplified but happened)... and therefore increased the need for food delivery etc.
Also, as cruel as it is, the less hungry people, the more people who need food.
In other words, the problem is complex and not simpel. So those who feel the need to solve it (I do a bit actually) should do it. But others who want to explore the mars .. should do that.
Both is important. But maybe mars is actually simpler, than sustainable solving world hunger. Btw. people also like electricity, houses, cars, education ...
I would argue both is interconnected. With exploring new areas, whether on earth or on mars, new potential spots for human life gets found/get made inhabitable. And even though human sustainable colonisation on mars is far away, we need to start sometimes. Maybe just to make it a serious vision, to give people perspective whi say humankind is doomed anyway as we cannot grow indefinitely ... we can.
But for sure there is lots of potential on earth, like the deserts or the sea (ground), before mars becomes a serious alternative ... nut it is all interconnected. Progress in one area of sustaining life in extreme conditions, benefit other areas.
Besides, there never was a time, when there was no hunger on earth. Now while it would be nice to achieve this, I don't think it is smart to stop everything else until we get there ... if we even can get there.