You've heard it said before, that someone 'missed the boat'. They just didn't seem to get it, whatever it was, or they didn't go along with the rest of the group's thinking and decisions. It was kind of no big deal, too bad for them, somehow they just missed the boat. That sort of careless usage was how I understood the phrase too, until our Larkspur years when Peter took the ferry into San Francisco every day. On most days we arrived just before, or as the last call for the ferry was announced. But there were a few days when we turned the corner into the ferry lot, sped around the ring road as fast as possible, and saw the ferry pulling out. Sometimes it was only a foot from the dock, almost close enough to jump, but the outcome had an absolute finality to it. We had truly missed the boat.
A somewhat similar, casually used phrase is 'down the drain'. Oops, there it goes; it was a wasted effort, as in the teacher got sick and cancelled the exam, and all my extra studying went down the drain. But again, that is not the usage I now associate with the phrase. Indeed, Mr. Rogers had it right. You can never go down the drain, even if you want to. And why would you want to? Because, in a flash, the only set of keys to your rental car fell from your hand, slid through the grate, and went right down the drain. Again the phrase contains an absolute, and this time even horrifying, finality. Luck was involved however. The drain was dry and the keys stopped in the catch basin several feet below street level, nearly hidden by the muck and leaves. Neighbors suggested calling Boston Water and Sewer, who sent a truck within the hour. Two guys worked as a team to hoist the grate, pull out the keys, and joke about a rat almost biting their hands while doing it. And that is why you would not really want to go down the drain.