It lost (most of) its rotation because it has no moon, nothing to counter solar tides. Because it lost its rotation, it lost its magnetic field. Because it los

It lost (most of) its rotation because it has no moon, nothing to counter solar tides. Because it lost its rotation, it lost its magnetic field. Because it lost its magnetic field, it lost its hydrogen. Mars lost its hydrogen the same way, because its core froze enough to kill its magnetic field. There is more than one way to go. Venus is in a bad way.