Why is there so much more carbon dioxide in the atmosphere of Venus than in that of Earth? Why so much more carbon dioxide than on Mars?

The reason for the more concentration of carbon dioxide in the atmosphere of Venus than in the Earth -

On the Earth, most amount of the carbon dioxide is in the ocean water and in sea sediments.

Considering Venus, in the planet Venus, there is no Ocean water, hence, carbon dioxide can not get dissolved into the water, hence, it is found in the atmosphere.

So, the escape velocity for carbon dioxide on Mars is smaller than Venus.