How did the Greens actually pull this off?

The Blacks' Houses:

- House Stark and the entire North

- House Tully and the entire Riverlands

- House Arryn and the entire Vale

- House Greyjoy and the entire Iron Islands

- Half of the Crownlands

- Half of the Reach

The Greens' Houses:

- House Lannister and the entire Westerlands

- House Hightower and Oldtown

- The Triarchy

- """""House Baratheon and the Stormlands""""" (literally AFK for 90% of the war)

The Blacks' Dragons:

- Caraxes

- Meleys

- Syrax

- Tyraxes

- Vermax

- Arrax

- Sheepstealer

- Vermithor

- Silverwing

- Seasmoke

- Moondancer

The Greens' Dragons

- Sunfyre

- Vhagar

- Tessarion

I have two questions for you:

1) How did the Greens pull this off?

2) How did Rhaenyra fumble this? Was she stupid?