If you received an unexpected windfall of money, you might think that there's no harm with investing that into risky stocks, or even just gambling with it.

But regardless of whether you win the lottery or spend years saving up money to invest, you need to be careful with what you do with it, because making sound financial decisions can help set you up for a better future down the road. And there are opportunity costs to consider as well, including the returns and profits you could be missing out on by making poor investment decisions.

A couple of stocks that I wouldn't consider investing in right now -- even if money did fall from the sky -- are Novavax (NVAX 2.52%) and fuboTV (FUBO -0.74%). Here's why these are two stocks you should stay away from now.

1. Novavax

Novavax stock has been a volatile investment over the past few years. There has been lots of excitement over its COVID-19 vaccine, but there have also been concerns about what comes next for the company. Shares reached highs of over $300 last year and today they're down around $40.

The stock nosedived earlier this month after the company released underwhelming quarterly results that also featured a significant reduction in guidance. What was concerning is that from a previous forecast that called for revenue between $4 billion and $5 billion, Novavax slashed that down to a range of $2 billion and $2.3 billion.

That's a catastrophic move that came with no prior warning. Although the company's vaccine obtained Emergency Use Authorization from the Food and Drug Administration last month, it isn't approved for use in adolescents or as a booster shot, and that is no doubt impacting its sales potential.

The company does have ongoing phase 3 trials for NanoFlu, but there simply isn't enough potential here to make the stock worth the risk. Novavax is incredibly volatile and has burned through $744 million just to support its day-to-day operations over the past 12 months, while also incurring nearly $1.5 billion in losses during that time.

Already down 84% in the past year, this is a stock I can see falling even further in the months ahead.

2. fuboTV

Another money-burning business that I wouldn't dare invest in is fuboTV. Its operating cash burn over the past year is $323 million, but the streaming company has far less cash and short-term investments on its books than Novavax does ($373 million versus $1.4 billion for the vaccine maker).

As a result, the situation may be even more perilous for fuboTV given its smaller financial buffer. fuboTV has generated $852 million in revenue over the past 12 months, but its net losses during that time totaled $475 million.

A big problem with the business is that fuboTV is spending too much on content; for the three-month period ended June 30, its subscriber-related expenses of $219 million were more than the $200 million the company generated from subscriptions. Once you add in other overhead and operating costs, there's little hope of the business turning a profit anytime soon.

A big part of the problem could be that unlike other streaming businesses, fuboTV's focus is on sports, which can be costly to win the rights to stream. The company refers to itself as "the world's only sports-focused live TV streaming service with top leagues and teams."

fuboTV's margins need to improve significantly before this growth stock can become a more tenable investment. It's not surprising that shares are down 85% in the past year and performing as badly as Novavax. Both stocks look like dreadful buys right now.