Doctor Doom's ultimate tragedy is that while he's rich and powerful beyond belief, he still can't be satisfied.

Source: https://www.cbr.com/marvel-comics-villains-worst-ridiculous-motives/

Doom's rivalry with Reed Richards has defined his adult life.

Source: https://www.cbr.com/marvel-villains-got-revenge-they-craved/

Of course, things are hardly that simple, as Hel's rightful regent is still very much alive, although there isn't much that Hela can do while in Doctor Doom's clutches.

Source: https://www.cbr.com/thor-doctor-doom-control-hel-marvel/