I think the fact that she had a huge salary is why she feels comfortable doing this. The average person needs their job to pay the bills so they don't want to rock the boat. She's already set for life so she doesn't care who she offends because getting fired is not a big deal for her.
Future employment opportunities still exist for her. That is another reason an employee may opt in to present an alternative reality online upon events like “leaving” or “getting fired” as people externally usually don’t have time or the access to verify either side’s story. There will be another equal caliber company where she can continue to do her work. Almost everyone who left Google in such public fashion in recent history have landed similar jobs elsewhere.
And let's not forget that in most(all?) of the other 1st world countries you are lucky if you make one tenth of that base salary. It's easy to forget. Very easy.
