Source: Facebook.

From an investment standpoint, Facebook (NASDAQ:FB) is on a roll. After a bungled IPO and subsequent questions about mobile monetization forced the company briefly below $20 a share, Zuckerberg and Co. have led the company on a tremendous run; its current price now sits above $90 per share. So, while long-term investors are ebullient, and for good reason, it's always a good idea to watch for hidden risks. To that end, we asked a few of our specialists for hidden threats to Facebook's investment thesis:

Jamal Carnette: Facebook's video ambitions could go awry.
While I really like Facebook's video growth, with Zuckerberg noting the company grew from 1 billion views per day in June of last year to 4 billion views a year later, and the company's native-video platform buildout that cuts Alphabet's YouTube out of the monetization chain, there's a risk that Facebook loses credibility with its advertisers in regard to the value proposition of this explosive video growth.

Earlier, it was revealed that the social-media site counts a view as 3 seconds. This low figure, alongside Facebook's autoplay function, cast doubt on the quality of what the company considers a view. Facebook did offer a few new options for marketers -- including a 10-second option and a 100% in-view option -- alongside an independent analytics firm, Moat, to measure views instead of Facebook providing that data.

There are other issues alleged against Facebook's video: The most damning is Facebook's inadequate response to "freebooting," or the stealing of content from original creators by Facebook users. While this doesn't generally affect marketers first hand, it does anger large, popular content creators Facebook needs if it wants to directly compete against YouTube. In the end, however, I feel Facebook will solve these issues, but investors should watch Facebook's moves carefully here.

Daniel B. Kline: Young people could flee.
My mother is one of the first people to comment on anything I post on Facebook. Even as a 41-year-old, that still feels to me a bit like having my parents want to hang out in the living room when my friends were over in high school.

The presence of adults makes Facebook inherently less cool for teenagers. That has sent some of those younger users to platforms like SnapChat and the Facebook-owned Instagram and WhatsApp. It's not a major problem yet, but it's one the company has acknowledged. "We did see a decrease in [teenage] daily users [during the quarter], especially younger teens," then-Facebook CFO David Ebersman said during a January 2014 call with investors, Time reported. That's a relative drop in the bucket and the often-predicted mass exodus still has yet to come, but it could.

By virtue of its ubiquity, Facebook is inherently uncool. It's still needed by teenagers because none of the other sites offer all the tools the social media leader does. That may be the case now, but it's not necessarily the case forever, and an upstart that keeps mom and dad away could cause young users to abandon Facebook.

They may still keep accounts to check in with older relatives and say happy birthday to grandma, but they won't use the site for daily interaction with their peers. It's not a guarantee this will happen -- another site needs to find a way to appeal to young Facebook customers wary of posting because mom and dad are watching -- but it most certainly could.

Tim BruggerAd blocking could hurt Facebook's monetization plans. 
Not surprisingly, the vast majority of Facebook's $4 billion in revenue last quarter was of the advertising variety. Despite efforts to ramp up gaming and app sales, and the pending release of its Oculus Rift virtual reality (VR) headset, Facebook is and will remain the king of social media advertising. A full 95% of last quarter's record-breaking sales were ad-related.

But what if a growing number of Facebook's 1.49 billion monthly average users (MAUs) opted to block ads? Though in its early stages, more and more Internet users are doing just that.

Worldwide, digital ads are expected to generate over $170 billion in sales this year alone, of which Facebook garners more than its fair share. However, as ad spending continues to grow, so too do the number of folks online that have downloaded ad blocking apps to skip the "noise." A 2015 study found a whopping 198 million of internet users worldwide now block ads, up 41% from 2014.

The adoption of ad blocking apps on mobile devices is considerably lower, but following the release of iOS 9 with its ad blocking compatibility, that could change in a hurry as other OS providers follow suit. At present, iOS users can only block ads via its Safari browser, so Facebook's app is safe... for now.

Daniel Kline owns shares of Facebook. Jamal Carnette has no position in any stocks mentioned. Tim Brugger has no position in any stocks mentioned. The Motley Fool owns shares of and recommends Alphabet (A shares), Alphabet (C shares), and Facebook. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.