I have no problem with the OP's line of reasoning.

It's obvious that Elon Musk has a larger than normal ego. I'm sure that this hands-on attempt to help probably greatly satisfied that ego but it seems reasonable that a monetary contribution could have done as much or more good while also appearing less selfish.

There was absolutely no reason for Musk himself to actually go to the cave either. Send some expert engineers along with your sub, sure, but I have no idea what help he thought he would be providing in person.