"I really like you, you're Ou Zun, you have status and identity, and I like you. But even if you were just a penniless kid on the side of the road, I would still like you. Just like you said, I will eventually become Jin Shi's daughter—my identity and status are clear for everyone to see, other men wouldn't dare set their sights on me. But did you ever think about your status and identity? Have I not also aspired to you?"
The reasoning is basically the same.
Moreover...
Mù Qiānxún really doesn't need money. Ever since she was little, Mu Xin always deposited a few thousand into her card. Over time, she's become somewhat of a little rich woman.
She has several hundred thousand to spare.
Because of her nature, Mù Qiānxún isn't too fond of clothes, bags, and jewelry that girls typically like. She barely spends any money aside from the essentials.
Just like how Ou Zun bought the top-quality equipment for her recording studio. Didn't she accept it?