I think its a because everyone enjoys recreation
The more allies Rome had the more territory it could have under its control. Also the other places bring new cultures into Rome so that it could grow in that aspect as well.
This is a very complex question, but they both collapsed due to:
decentralization and government corruption
plagues/ epidemics
high taxes
and invasions
Some differences are that the Chinese empires saw a revival while Rome didn't.
If by South Africa you are referring to the Republic of South Africa, then their transition to Democracy was a bit rocky. It was a part of the British empire before they gained their independence as a free republic. This free republic however was not a democratic one due to things like apartheid rules where a minority of rich people who were mostly white controlled the government at the expense of the local African majority. As the fight for democracy continued many things started coming up like huge unemployment and infringement of human rights. Apartheid ended and currently the country is a democracy with suffrage, but there is evidence of high corruption among the government employees and the administration. Expand those ideas into an entire essay.
Nazis and Fascists both believed that what they were doing was for the betterment of their country.