Everyone else is doing better than Snap Inc (NYSE:SNAP) — at least according to a recent ad buyer survey from Wall Street investment firm Cowen, which just released a strongly bearish report on SNAP stock.

In a recent survey, Cowen asked 50 senior ad buyers to rank social media networks by key metrics, such as return on investment, targeting, and data, analytics and measurement. Snap ranked dead last across the board. Behind the likes of Facebook Inc (NASDAQ:FB), Instagram and Twitter Inc (NYSE:TWTR), among others.

But the bad news doesn’t stop there. According to the survey, 96% of ad buyers would prefer to advertise on Instagram Stories over Snapchat ads. Moreover, over the next 2 years, Snap’s social ad spend share is expected to increase just one percentage point from 6% to 7%. Instagram’s social ad spend share is expected to increase 5 percentage points from 15% to 20%.

Overall, the survey painted a really ugly picture for SNAP. That is why SNAP stock has dropped more than 5% since Jan. 3.

What’s next for SNAP stock? Likely more downside. Here’s why…

Competition Is a Big Problem

The results of Cowen’s survey align with my feelings about SNAP stock.

This is a stock struggling in a highly competitive digital advertising market. While secular growth in the entire market will propel positive revenue growth for Snap, such revenue growth will be tepid compared to peers at scale, due to Snap’s inability to produce competitive ad products.

This is why Snap’s revenue growth last quarter (62%) was only marginally higher than Facebook’s revenue growth (47%), despite Facebook having a much, much larger revenue base.

This problem will only get worse in 2018, as Amazon.com, Inc. (NASDAQ:AMZN) makes a big push into the digital advertising market. Amazon’s entry only makes the market more competitive. And Snap, which is already struggling, will likely be one of the biggest losers.

Age Is Also a Big Problem

But competition isn’t the only thing plaguing SNAP stock. Age is a problem, too.

Bulls love to point to the fact that Snap has super-high engagement among the all important 13-to-34 demographic. Cowen’s research largely supports this. Relative to other social media platforms, Snap has above-average engagement in the 18-to-24 demographic.

But Snap has lower-than-average engagement in every other age demographic.

And that is a serious problem, especially since Snap has already reached 70 percent penetration in the 13-to-34 demographic in the US, UK, France and Australia.

What happens when all those kids grow up? Are we really going to be a society of 35- to 45-year-old social media addicts running around snapping disappearing photos?

I don’t think so.

Yes, Facebook managed to “grow up” and go from a college kids’ platform to something essentially the whole internet world uses. But Facebook has universal appeal. It’s designed to be the town hall of the internet. It’s basic, straightforward, sports a professional design and essentially everyone can extract utility from the platform, whether it be through keeping track of family members, connecting with friends, reading news, watching shows or doing any other number of things.

Snap is trying to do that, but it’s not set up to be a town hall that appeals to everyone. The design is inherently playful and “kiddish”. Get rid of that and you lose the reason why kids love the platform. But don’t get rid of it and the platform will never be attractive to the 35-plus crowd.

It’s also important to note that Facebook grew up in a time when there wasn’t already a social media behemoth that acted as the town hall of the internet. But now there is such a social media behemoth.

In other words, Facebook wasn’t going up against Goliath. But Snap is going up against Goliath and all of his big buddies (Instagram, Twitter, and now Amazon).

There simply isn’t room for Snap to grow up. Even if consumers at older ages do love the idea of Stories, why wouldn’t they just use Instagram Stories? It’s designed more professionally. It has more users and a wider reach. It also connects seamlessly with Facebook, which everyone has.

Overall, Snap’s user growth prospects look greatly limited. This currently isn’t an app that everyone uses, and it never will be an app that everyone uses. It will forever be an app that teens and young adults use. But Snap is already capturing 70% of that demographic in developed markets, implying user growth potential is limited from here.

Bottom Line on SNAP Stock

Without user growth, Snap needs to dramatically increase average revenue per user in order to justify its valuation. But Cowen’s recent ad buyer survey indicates that average-revenue-per-user growth prospects are also greatly limited.

So where will the growth come from to justify the valuation?

It won’t.

Hence, there is no reason to own SNAP stock at today’s stretched valuation. Competition is only growing, and limited user growth remains a serious headwind to explosive revenue growth.

As of this writing, Luke Lango was long FB and AMZN.