Because the other large players are so large that they will either buy you out or legally stamp you out of existence before you can gain significant market shar

Because the other large players are so large that they will either buy you out or legally stamp you out of existence before you can gain significant market share. And farmers aren't going to be easy to convince to drop $100K+ on a tractor company with no history, no reliability metrics, and no guarantee the company will even exist in 20 years when something major breaks requiring more expensive custom manufacturing. It would take 100 million or more dollars in capital to even start a new heavy equipment company before you even start dealing with all the legal costs and requirements of staying in the market with the other big players.