From the snippets of text I've seen in various articles, it just sounds like she was bored? I imagine she had worked for a number of years and saved up a decent amount of money and decided to leave her job, had nothing to do all day and just posted at a Starbucks working on personal projects, which ended up including hacking into large corporations...?

Reminds me of my first manager, who was mid/late 30s and could've retired very comfortably long ago, and his primary motivation for working was because boredom, for him, would've been (in his words) a dangerous thing.