Brian Balfour, Founder & CEO of Reforge and former VP of Growth at HubSpot, joins Mostly Growth to explore why product-market fit is a moving target. He introduces the concept of the Product-Market Fit Treadmill, a state where rising customer expectations and competitive pressure make it harder than ever to stay ahead. Brian breaks down how AI has accelerated PMF collapse, explains the hidden costs of product adoption, and shares how Reforge shipped five AI-native products with a team of just 20 people. Packed with frameworks, strategic insight, and startup realism, this episode is essential listening for product leaders, operators, and founders navigating the next wave of GTM.

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LINKS: 

Mostly Metrics: https://www.mostlymetrics.com

CJ on LinkedIn: https://www.linkedin.com/in/cj-gustafson-13140948/

Growth Unhinged: https://www.growthunhinged.com/

Kyle on LinkedIn: https://www.linkedin.com/in/kyle-poyar/

Brian Balfour: brianbalfour.com

Brian on LinkedIn: https://www.linkedin.com/in/bbalfour/

Slacker Stuff: https://www.slackerstuff.com/

Ben on LinkedIn: https://www.linkedin.com/in/slackerstuff/

https://brianbalfour.com/four-fits-growth-framework

https://x.com/amasad/status/1981201454032703662?s=46

https://getlatka.com/companies/firefliesai

https://x.com/rowancheung/status/1988218743952916537?

https://gamma.app/insights/how-we-built-a-usd100m-business-differently

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RELATED EPISODES:

When the marketing math doesn’t math | with Emily Kramer

https://youtu.be/sSuoV_YSrlw

Why Founders Are Posting Sad Dinners

https://youtu.be/Zl6NSIHF2Gk

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TIMESTAMPS:

00:00:00 Preview and Intro

00:01:15 Sponsors – Pulley, Metronome

00:03:36 Guest Introduction – Brian Balfour

00:06:24 Writing, Frameworks, and Career Foundations

00:09:56 PMF Misconceptions and the Treadmill

00:13:25 AI Acceleration and PMF Threshold Shifts

00:16:07 CRM Expectations and Changing Market Dynamics

00:18:53 AI-Native CRM Approaches and Workflow Changes

00:21:08 R&D Investment and Customer Expectations

00:23:37 Roadmaps, Feature Velocity, and Customer Education

00:26:02 AI Adoption Across Product Discovery, Delivery, and Adoption

00:27:17 Product Adoption Constraints and Human Bottlenecks

00:29:06 Platform Cycles and Distribution Shifts

00:31:05 Framework for Evaluating Platform Bets

00:33:20 Open–Close Platform Dynamics in AI

00:36:34 Emerging Platforms and Early Ecosystem Bets

00:39:10 AI Discovery Channels and Traffic Distribution

00:40:03 Distribution Shifts and OpenAI’s Multi-Channel Bets

00:41:15 Hiring, Resumes, and AI-Generated Applications

00:43:20 Note-Taking Apps, Market Size, and “Flintstoning”

00:46:06 Vertical AI Note-Taking and System-of-Record Paths

00:48:27 Gamma, Canva, and AI Presentation Tools

00:50:15 Onboarding Innovation with AI Agents

00:51:57 Closing Remarks and Outro

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SPONSORS:

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