My comment was based on a more precise point, namely that #3 in the process below is very natural: 1. Assume the theorem is false. 2. Make some calculations ba

My comment was based on a more precise point, namely that #3 in the process below is very natural: 1. Assume the theorem is false. 2. Make some calculations based on that assumption. 3. Eventually, make an error. 4. Pursue that error to a contradiction. 5. Claim victory.