We can and will leave this planet at some point or we will cease to exist as a species. Can can absolutely build vertically and should so far as modern farming solutions go. You're and agriculturist. You know how much food we (humans) waste on an annual basis. Food scarcity is not a problem. It's the manner in which we produce, distribute and consume that need be made more efficient. Technology doesn't stop. Everything trends to the marginal cost of production and technology makes that cost cheaper every day.