The "You love your prison" EST scene encapsulates Elizabeth's character so well.

Philip's EST sessions make him feel like he made a terrible choice entering into this life. Ironically, Elizabeth hates EST, but she is the one who leaves her session with a feeling of self-actualization (even though she would never admit it).

Listening to the EST leader talk about our lives being prisons of our own making, but prisons that we ulitmately need and feel comfortable in, you can tell Elizabeth feels "seen." She realizes that, yeah, she feels trapped by her life sometimes, but given the choice to go back and do it differently she'd make the same choices again. She believes in the cause that strongly, and also without this life (or the cause) she has no idea what the hell she would do when she gets out of bed in the morning.