April 1912 (Titanic) - "unsinkable ship"
June 2023 (Titan) - "unparalleled special feature"
Both of them did not escape the tragedies in Atlantic. I think this ocean is the most expensive graveyard on Earth, since it took billionaire's life. Anyway, are you going to risk your life in a submersible ship without further research? Imagine a ship that is controllable by a PSP remote control and the worst it was a bluetooth device. You are paying 250K usd for a single trip with lots of risk, a bad decision for the billionaires.
Here is the picture of their navigation devise.

And did you know that Mr. Beast declined to join in this tragedic trip?
YouTube’s richest creator MrBeast says he declined a spot on the doomed Titanic sub dive: ‘Kind of scary that I could have been on it’
I think he noticed the security and safety of the said ship.
Conclusion: They underestimated the depth and pressure of the ocean. They did not go throughout a standard operation. They wasted life, an expensive journey to death. Rest in peace billionaires. And let us also give peace to the souls that are now resting in a disastrous event in ocean.
Article for Mr. Beast:
https://www.google.com/amp/s/fortune.com/2023/06/26/mrbeast-youtuber-declined-spot-titanic-titan-sub-implosion-oceangate-jimmy-donaldson/amp/