The investors got exactly the behavior they wanted. They let (encouraged? obliged?) the founders to take money off the table so that they would double down on a

The investors got exactly the behavior they wanted. They let (encouraged? obliged?) the founders to take money off the table so that they would double down on a high-risk/high-reward go-big-or-go-bust strategy. The Founders did that, and the dice broke against them. They absolutely should not give the money back, and no one should give them a hard time about keeping it.