I'll say it again, Nick has unresolved childhood trauma issues regarding his mother Celeste as most pathological narcissists do. It can only be two possibilities. She was either an "absent" or "dead mother" emotionally unavailable to him as a toddler, or she coddled/smothered him, and he was never able to fully separate from her and become an individual.
I've poked at him over the months in stream chats about his perceived "mommy" issues, and most responses have been things like "I don't have any mother issues", "I had a wonderful childhood".
The bottom line is he knows she's the golden ticket to furthering his lazy, libertine depraved lifestyle, but I will almost guarantee he deeply resents her. Bob seems to be more of a door mat codependent type. "Yes Dear" Whether it's just people pleasing for the comfortable lifestyle, or he's fucked up too not sure, but This fits the narrative that Celeste herself is also a narcissist.