Gonna go hard in the paint on pretentious symbolical analysis that I usually don't like, but this film demands it.
For me the scene at the sea and the disillusionment in how he turns around is I think a kind of existentialist statement. Life not as a final battle won but Sisyphus constantly pushing the rock up the hill. The sea represents all kinds of things but the point is that all the things it might represent are meant to be end goals, that are supposed to have a kind of satisfying finality that, according to the film, doesn't really exist. The sea could be just the beauty of the sea, the sea could represent liberation, the sea could represent maternal mother's love--an expression of the death drive (the sea is also associated symbolically with death) which is the unconscious wish to return to the womb/an immaterial state of pure freedom. Living in a culture that programs us to go for some kind of "final solution" through various narratives, we are surprised, as Antoine is, when the thing we unconsciously thought would bring us such satisfaction, be it this or that actual thing or this or that abstract ideal, ends up not fulfilling us. Our drives for these feelings/places/states take various forms. The typical Freudian stance would be that the healthy, non-neurotic individual realizes consciously or unconsciously that his desire for death/immateriality/the womb/a return to innocence has to be rerouted and projected back onto the temporary, fleeting, moment-by-moment satisfactions of life. Rather than return to the mother's womb/death, the mature drive is turned into a drive towards sex/procreation/making a contribution to society. Maybe the rest of the Antoine films show his progression from disillusionment with final answers towards a willingness to engage life.
Notice how often I used the word drive in this post, and my obsession with other films heavily associated with driving and fucked up sexuality (Taxi Driver, Drive, The Brown Bunny). I think as long as I don't start writing essays on the Fast and Furious series I'm okay.
Well I don't think I can contest much of this really. And I prefer this kind of reading as well where the essence-distilling, often symbol-heavy significations (that pettily vie for more explanative power than the next one; "what does the sea represent") are maybe engaged with initially and then more or less made null in favor of a more elusive and process-driven truth - one that is primarily experienced
by both character and viewer. I feel like my conclusion hinted at something similar, but maybe I should have followed up on it.
I am somewhat confused by the categories of opposing pursuits you set up though. Just to touch on the bolded (and I realize you specify that the view is Freudian and, by that token, not necessarily fully shared by you): Do you not think someone could treat these as a kind of "final solution" just as well? Like having finally procreated or having written that impactful book or having passed that important law, could one not emerge as unfulfilled as from any other activity? I'm guessing the heart of the issue here is more about how
goals are approached rather than what they are (altogether, including the Freudian ideals).