I believe your speculation is correct.
The DAO was a great idea but it should have been done at a significantly smaller scale. Raise say $1M worth of tokens and invest in three things and then sunset the project and evaluate the result. Call it an experiment. This was like going from bottle rocket to Saturn V in one step.
The only explanation I could imagine is like: "We could have become rich if we knew that Bitcoin would be a success..now it is too late. But wait, there is a new thing called Ethereum, maybe that is our chance! Let's invest our money!".