By Allison Schrager

If the bad news is that members of Generation Z can’t afford to buy a house until they are middle-aged — which isn’t really bad news, honestly, but anyway — then the good news is that at least they are investing their money in high-performing assets. Or so we thought.

Now we are learning that they might not be very good investors, or even investors at all: According to a new survey, more than half redirected funds to sports gambling, which a quarter consider to be part of a long-term investment strategy.

All of which raises the question: How did they get it so wrong?

The survey, from the personal-finance company Betterment, polled 1,000 existing investors evenly divided among baby boomers, millennials, Gen X…