You're making my point. You can buy a good used pickup for $10K and put the other $40K in your farming (or whatever) business. If you're a good businessman, you don't spend business capital on personal luxuries. And if you do buy additional land or equipment, you had better make sure that you don't need that cash down the road.
How taxes work: you make $X, you owe $Y regardless of whether you reinvest the money you make, put it in the bank, or set fire to it. You don't "pay all your profits to the government in taxes" regardless of what you do with those profits. By earning such profits, you incur a tax liability, which is an amount that is a percentage of those profits.
The fact that farming requires large capital investments and good management of that capital tells me that far more people are doing it than actually should. Tucky Buckford thinks that just because he grew up fucking sheep, he knows how to run a sheep farm. Farming, like many other industries, would benefit from consolidation because of economies of scale. Right now, though, thousands of individuals producing farm products is like an auto industry where thousands of people build one or two cars each per year in their garages. Inefficent.