Round earthers all believe the same thing? That's a laugh! There are just as many variations of RET (if not more) than of FET.
Some things that round earth people are generally in agreement about that flat earth people generally have no coherence in their group view:
The size of the Earth
The layout of the countries
The existence of Antarctica
The orbit of Earth round the Sun
The orbit of the Moon round the Earth
The distance of the stars
I could go on, but I can't be bothered.
And before you start nitpicking that "some people think the stars are only about 100 miles away and the moon is cheese, even though they think the earth is round" I'm not talking about people who have differing beliefs through ignorance. If you got someone who thought the stars were 100 miles away, and sat them down and explained clearly, using examples they could understand, that science can demonstrate their distance and how it does it, after that they would believe what science has shown them. Flat earth theory fails to be able to do anything like that and that's why people will always be more likely to believe round earth theory, even if it isn't true - because it can be demonstrated to at least appear to be true within the limits of provable knowledge.