Naw. We need to be very careful with these sorts of sociological/psychological just-so stories which pass off to individuals and the species responsibilities which lie elsewhere. We need to be very careful of any narrative that attributes particular events to some nebulous fault of human nature, so in need of "grace", rather than the particular institutions and individuals who actually made the decisions and set the policies which brought them about.
The real reason people didn't respond the same to that ship capsizing in the Mediterranean as they did to the Titan sub isn't "crowd mentality"; it's because they didn't know anything about it, because the press barely covered it.
The real reason that sub got a huge rescue effort and that refugee-ship didn't isn't because there were fewer people on the sub and we all knew their names and saw their faces(cuz the press Did Not Stop Talking About It for Days, while NOT talking about the refugees; not even trying to find their names, let alone pictures of them); how would it when none of US have the authority to deploy those resources?! The real reason was because States, and the Politicians who run them and DO have that authority, chose to deploy those State Resources to rescue the rich people on the sub -even though they knew, for a fact, they were certainly already dead- and chose NOT to deploy those resources to save a boatload of refugees who WERE Alive and who they COULD Have Saved, because they didn't want those refugees in their countries anyway.
Read This Article, and ignore the victim-blaming in it. Frontex, the European Union's border-agency, had seen the ship about a day before it sank, and the only response the EU could muster was a(ONE!) Greek coastguard vessel. For HUNDREDS of refugees. They KNEW the condition of this craft was poor, yet further rescue resources were not called up, were not prepared, were not sent out in preparation of this ship sinking to ensure people were saved; the Greek Coastguard asked all nearby ships to help If They Wanted To, but that was it. And the whole REASON they were trying to cross in a boat too small to hold them all in the FIRST Place was because of steps taken by the EU, by those States and the Politicians running them, to stop those people(refugees primarily from Afghanistan and Libya, places destabilized by EuroAmerican colonial adventures, as well as Syria, Pakistan, Egypt, and Palestine) from coming to Europe by safer means.
And why were those steps taken? Why were those safer means barred? Because people voted for those policies. And why would the people of Europe vote for something so monstrous? Because the people of Europe, for over 20 years now, have had Politicians and The Press pounding it into their heads that "Immigrants are Dangerous", that "Immigrants Cause Poverty and Disease", that "Near Easterners, and Africans, and Central Asians, and above all MUSLIMS, Aren't Like You and Can Never Fit In and Want To Destroy Our Way Of Life." And why have Politicians and The Press been spreading such inhumane, such irresponsible, such callous and cruel lies? Because Billionaires pay them to!
This disparity is not the result of general in-born human psychology which we must All take the blame for, and All work on in-our-selves to better. Future tragedies like this will not be prevented by self-improvement; they will be prevented by political action to stop the tragedies and remove power from those responsible. This disparity, This tragedy, was the particular product of the particular action of particular people who should NEVER have the power to do this again. They are the result of institutions which raise-up and celebrate The Rich as "Special" and "Important" and "Heroic", while demonizing The Poor as The Other and a Burden and Unneeded, because Rich people control them and Rich people would really rather prefer it if everyone not being immediately useful to them would Just Die Already.
