The best thing about farming is that it allows you to become an eccentric -- everybody around you expects this -- which is enough all by itself to gradually make you rich.

Consider:

• Farmers typically stay on the same farm forever, thus relieving themselves of the expense of buying a bigger McMansion every few years. For most people, buying houses they don't need is the stupidest waste of money in their lives.
• Buy a fancy new car? When your gravel road is going to ding it up and it's always going to have half a ton of feed or livestock in the back? Are you crazy? Besides, no one expects you to. Everyone smiles and waves when you drive by in your elderly pickup. That takes care of the second-stupidest waste of money.
• Nor are you tempted to buy a flavor-of-the-month politically-correct car, like a hybrid. Where does the half-ton of feed go? Even the most repellent snob won't begrudge a small farmer his 10-mpg pickup truck. Face it, you're surrounded by a cloud of political correctness (and possibly smoke from your worn rings) wherever you go.
• And the same goes for clothes, too. A farmer doesn't gain any points for wearing the latest fashions.

So even if your part-time farm never makes a dime, it provides you with a tremendous level of social approval for living like a cheapskate. If you take the slightest advantage of this, you're likely to retire rich.

(Assuming that farmers ever retire. I think they live forever.)