Wind and tsunami waves move naturally around a round building rather than getting caught at (and potentially ripping off) corners. A rounded roof avoids ‘air-planing’- a situation where a strong wind lifts the roof structure up and off of the building.
There are dozens of interconnected points in a round home. These are sites where builders can connect parts of the building together. In the olden days, the connecting materials were rope, vine and hides. Modern materials are engineered components- like a center radial steel ring, steel brackets, Seismic and hurricane ties, bolts and steel cables. These connect the structural pieces and give the building a unique combination of flexibility and strength- qualities which causes them to be significantly safer in severe weather conditions like earth quakes, extreme winds and heavy snowfall.