Founders can’t resist showing off their TAM, SAM, and SOM slides to prove the size of their market. What if I told you those acronyms are keeping most founders blind to their real market?
I was reminded of this in a recent conversation with a senior retail executive.
This person works at the intersection of retail and technology, yet had no idea what a Chrome extension was.
At first, I was shocked. As a founder who’s building a business around a Chrome extension, it felt almost impossible that someone in their role had no idea it even existed.
That moment made me realize that I’d lost touch with reality outside tech.
In the tech founder echo chamber, we assume everyone is like us. We obsess over AI eating the world, yet still only 30% of workloads run in the cloud. That gap between what we see as obvious and what the market actually shows is the real danger in market sizing.
The TAM/SAM/SOM framework creates a false sense of certainty.
Yes, TAM tells you how big a market could be in theory. SAM shows you what’s serviceable given your current product and distribution. SOM tries to ground it in reality by factoring in competition and resources.
But here’s the catch: markets aren’t static. They’re dynamic, constantly shifting. TAM/SAM/SOM locks you into a snapshot that’s already outdated.
You should instead be looking for what I call your GUAM: Growing and Underserved Addressable Market.
That’s usually where competitors aren’t paying attention and where the biggest opportunity lies.
How do you uncover your GUAM? Try this:
Start with behavior, not assumptions. Talk to personas who aren’t the traditional early adopters. What tools confuse them? What processes are painfully manual?
Map constraints. Ask yourself: is my market artificially constrained by a channel, feature, or technology? (e.g. “only Chrome users with extensions installed”).
Unbundle outcomes. Don’t think about the tool you’re selling. Think about the outcome customers want. AI is accelerating this shift. Can you deliver results directly instead of training users to master tools?
Track growth signals. Look for niches that are expanding faster than the broader market. An underserved segment + rapid growth = leverage.
Run small bets. Experiment with campaigns in those overlooked segments. Even modest traction could be a strong signal.
When you chase TAM/SAM/SOM, you risk ending up in the same crowded space as everyone else, fighting over scraps. When you uncover your GUAM, you put yourself in a compounding position, serving a market that needs a solution today and that will accelerate tomorrow.
That’s how you find product-market fit others miss.
That’s how you accelerate.