In Breaking Bad, Walter White was complex because he was a trusted member of the community (teacher) and a loving father, yet he was making and dealing meth. But he was motivated to do so because his health insurance wouldn't cover his treatment or provide for his family.
I think if you replace the word "complexity" with "motivation," the concepts you're trying to explain would become a lot more clear and self-evident. Indeed, "motivation" springs a lot more easily from Simon Sinek's idea of leading with "why" than does "complexity."
Great idea Martin, "motivation" is a great place to look and also think about Complexity. It's wonderful if that term helps you better remember and grasp the meaning of Complexity, and I hope your sharing it might also help others in the community too.
In case you're wondering though, I'll also share our thoughts as to why we chose the actual term "Complexity" here.
Complexity is about looking deeper—depth. There needs to be a depth to the desire if we wish to sustain the audience. We need to give our characters dimension. They can't be simple or flat. The WHY behind the desire then is the strongest and most critical place to start.
And we can apply this to your example with Walter White in Breaking Bad as well. He's more than a just a meth-dealer who wants to make money. He's more complex and has more depth than what it looks like at face value. He's also a loving father who wants to provide for his family. He also is facing a serious illness and is confronting his own mortality and what he's done during his life.