One of the things that I never stop thinking about is the lack of any “happy” endings in Black Sails (putting aside Schrodinger’s Flint and Silver’s role in that. It’s been done). Madi is the most obvious one to me: time and time again she demonstrates how willing she is to sacrifice everything for the cause and the war including her own life - a decision that is taken from her by Silver’s actions instead replaced of the treaty which she explicitly rejects multiple times and is in complete opposition to what she’s tried to achieve. She’s also entirely alone in her opposition to the treaty, putting her in a position where she either becomes Silver’s wife in Treasure Island, leaving her entire life behind to run an inn or (if you make Max Silver’s wife in TI) being the sole person still trying to achieve the same goal that previously had money and ships and fighters backing it.
Anne and Jack are slightly less obvious. Jack’s obsession with being remembered and having an important legacy is brought crashing back to reality in the Gurthrie’s parlour with the realisation that people are far more interested in lies that paint his friends as monsters than any resemblance of the truth - Flint’s vision of the future coming true before he even speaks it. The flag that everyone associates with piracy - his main legacy - is “fine” and the future of piracy in Nassau essentially has to remain a secret (when I can only imagine he wants to yell from the rooftops that he fucking won). Anne!! The amount of times she expresses the desire to leave piracy behind with Jack and have something away from that life and the amount of times Jack promises her that once he accepts the pardon so he can keep his name and then once they defeat the governor, then that’s it. And instead - they carry on. Because if Jack does of course she will follow! And because Black Sails is a show that follows the vague contours of history, pretty soon Jack is hung, Mary has died and Anne is imprisoned for thirteen years (depending on how you view the historical debate around her fate, that’s just my personal view).
And of course, this leaves Max (with her ending being the best on the surface) with the people closer to her having disappeared. Her existence is still very much built on sand and looking to history England returns to Nassau, and all she’s built will be gone. Ultimately, Vane is right, the empire survives on the idea of trading submission for comfort - but even that isn’t true! That traded comfort doesn't last for a meaningful amount of time and she's back to the same place she started.