Unless they were totally crazy they wouldn't leave it voluntarily. I suspect the worst.
Even a large boat can be subject to the whims of wind and waves The guy getting tossed overboard in the video at Jupiter inlet died, and there wasn't even a storm.
The only reason I can think of that they might have voluntarily left the boat is if it were within sight of land when it capsized and they tried to swim for shore.
That might be fine in a lake but it doesn’t sound like a good idea there.