That sort of thing in the public markets would prompt an SEC investigation for insider trading (despite it being "their money"). In the startup world it comes down to, these are not folks investors should be trusting.
Or "trust these guys: if they fail, they won't bullshit you and just give you the money they have remaining back."
It's all about perspective. Luckily, most investors don't think like you. Ones that do don't survive that long in the business.
I'm the sort of founder that thinks it's my duty to return value to shareholders. I should make money when my investors make money. I would argue that is the only perspective that survives the long term in business. Riding hype waves to enrich one's self without producing real product, that's not sustainable.
I know we're all founders here and would love to get the kind of deal the Secret guys negotiated (or Groupon, etc.). But it's not healthy for our industry. Basically the arguments in support of these guys is, well the investors knew what they were getting into. But that could be said for any scammy move by a founder. If they're trying to "do the right thing" they should return all the money to investors, minus a reasonable salary.
You can be a founder that thinks it is your duty to return value to shareholders and still take money off the table. In fact, there are situations where not taking money off the table hurts your shareholders.
Example: you're a poor founder with $400K in loans and 0 in saving, you're running a startup with good traction. You get a $20M acquisition offer and you accept it thinking it lets you clear debt and not be super poor anymore. Problem? Your investors barely get their money back so an exit you consider successful is not that successful of an exit for your investors.
Now imagine the investors let you take $1M off the table to clear debt and get a little comfortable. Now when the $20M offer comes in, it is easy for you to turn it down because you aren't in debt and you have a decent life. As a result, you end up building a $500M company. Your investors come out ahead because the equity they got for $1M cash you took off the table made them $10M, not to mention it gave you the mindset to turn down the $20M acquisition offer.
For many funds, they would rather you fail trying to make a company that is valued at $500M than be successful in building a company that is only worth $20M. Letting founders take cash off the table can help founders think as big as their investors do about the max potential of the business.
As Mark Suster put it, "Not FU money, but 'feed the family' money." What these guys got was FU money.
And the definition of "money off the table" is "keep it if things head south," so it's pretty hard to begrudge them for obeying the terms of the deal.