The joke of Estinien not knowing that he's scammed on prices is funny. But I also think he knows and doesn't care that much, because he has enough money and for him it's just a means to an end. He rather spend extra money so someone else is better off.
However, I also think it's a symptom of him not having thought much about his future, and still not doing so
Then again he probably knows that and feels incompetent compared to 'perfect' Aymeric, and feels ashamed to talk about it at all. He's 32 and he should've figured out his life by now. But he never had the time to really think on it
He likes to love others, but doesn't allow them to love him back, by keeping them at a distance