A possibility: Some of these richest-of-the-richest have seen and done most everthing, acquired everything they ever desired (and more) and traveled most everywhere. Many are risk-takers and some are outright thrill-seekers. Without constant and/or ever larger challenges, they become bored, "empty inside" and constantly seek SOMETHING that will - even if only momentarily - lessen or distract them from their boredom and emptiness, "make them feel alive"/excite them and earn them notoriety and the envy and adoration of others. An "exclusive adventure" like this submarine Titanic tour would fit the bill, perhaps even moreso BECAUSE it's risky and would, in a way allow them to meet and defy Death (the ultimate challenge).
A possibility: Some of these richest-of-the-richest have seen and done most everthing, acquired everything they ever desired (and more) and traveled most everywhere. Many are risk-takers and some are outright thrill-seekers. Without constant and/or ever larger challenges, they become bored, "empty inside" and constantly seek SOMETHING that will - even if only momentarily - lessen or distract them from their boredom and emptiness, "make them feel alive"/excite them and earn them notoriety and the envy and adoration of others. An "exclusive adventure" like this submarine Titanic tour would fit the bill, perhaps even moreso BECAUSE it's risky and would, in a way allow them to meet and defy Death (the ultimate challenge).
Their Hubris will be their undoing!