Robots have been there many times. Building a TRIESTE III for the sole purpose of taking people back there would be just to fecking expensive to be worth it.
I remember getting a blast out of “The Blue Planet” stop-action sequences from cameras set up way down on the abyssal plain that demonstrated the day/night and seasonal changes that became visible even way down there.
I know we’ve sent robots, but sometimes it seems Western civilization is wussing out and losing that urge to explore with manned missions.