The current pace of technological progress means that you cannot just sit and wait for the crops to grow. You need to constantly be learning a new skill on the side, diversifying your income streams, thinking and researching about how to optimize your costs and yields for the following year, etc.

This is because there is no guarantee that you can keep living the same routine till the day you die.

Also, humans are builders. Doing nothing and waiting for the seasons to change like cows in a field might not be in our DNA. Restlessness is our natural state, that's why we have all this stuff.