A recent survey found almost a third of millennials aren't doing as well financially as they thought that they'd be ten years ago. Because we're all optimistic when we're young, and think we'll be millionaires someday. Then REAL life sets in. GROAN!

Here are four of the biggest mistakes young people make with money according to Business Insider:

1. Taking a carefree approach, so you have to play catch-up. Like someone who decides to start saving for retirement LATER, once they're making more money. Then before they know it, they're 40 and still don't have a plan.

2. Creating a lifestyle focused on spending instead of saving.  It's more common now because of the whole 'fear of missing out' and 'YOLO' mentality. So you end up spending all your money instead of saving 20% like you're supposed to.

3. Relying on credit cards too much, and not paying attention to your credit score.  Building good credit is important, because you end up with lower interest rates later.  Which makes it easier to buy a house, or get a loan when you need one.

4. Not preparing for emergency expenses. Which goes hand-in-hand with taking a carefree approach and being too optimistic. Then when something happens like you lose your job it's immediate panic mode.