Things that go bump in the night...
I suspect that almost every sailor uses GPS these days; even though we can get by without it, it sure makes standing a navigation watch easy compared to the old methods.
I tell my students that GPS is a $12 billion Satellite Navigation System that will show them precisely where they have run aground! The point being that GPS is a navigational aid, not a navigator. Somebody still has to take responsibility to continuously monitor and check the vessel's position and progress. For whatever reason, it looks like the crew of Aegean failed to do that.
I don't know if we will ever know for sure what happened, but I suspect that an autopilot was doing the steering as tracking data shows the vessel following a straight course into a stone cliff.
Machines are fickle things. Just as your favorite gun would as soon put a hole in you as it would a target, your autopilot would just as soon steer you into a cliff as a channel—If you let them.
Not a good way to end a cruise.
-fl