A lot of interesting takes. I think the main point of this scene is to establish Andrews motivations; why hes obsessed and why he endures the abuse. Its not enough for him to be happy, its not enough to do a good job. He wants to be the greatest, to be remembered long after hes gone. Its something his family doesnt understand, which tracks because they are mostly just ordinary people who are not likewise obsessed with the pursuit of greatness. None of them are going to remembered after they are gone because they are content with not being the greatest. But thats not Andrew. For better or worse, however one might view it, Andrew is driven to be the best no matter the personal cost. Theres more than just that going on in this scene but for me, thats the main purpose and takeaway of the dinner scene.