Nah, it’s a white elephant.
If he didn’t know the value of it, by keeping it under his bed, there is no way that he could have known the value of it on the market nor how to reach the right buyers.
To me, it’s obvious that whomever bought it only gave him a relatively small fraction of its worth. He probably still made a couple of million from it, so he still did well for him.
Someone once said that the pearl is "the brilliant sarcophagus of a worm."
I'm wondering how big that worm must have been.