In this engaging interview, Yasith Vidanaarachchi, co-founder and CTO of Quantuma, shares his journey from tech giants to startup founder, highlighting the importance of feedback, networking, and resilience in building a successful AI-driven financial market solution. Discover practical insights on navigating the entrepreneurial ecosystem, overcoming challenges, and shaping innovative products.
You can have the résumé, the technical chops, and a product that works, and still hear a room full of smart people tell you that you don't have a business. That's what happened to Yasith Vidanaarachchi. After years engineering at Google, Meta, and Amazon, he finally went all in on building something of his own, only to hear from YC that a good technical product isn't enough. What makes his story worth your time is how he took it. He doesn't just survive harsh startup feedback. He goes looking for it, because he knows the nicest people in the room are the ones who let you build the wrong thing for months.
Today he's the cofounder and CTO of Quantuma, building deep reasoning AI that helps financial firms make sense of their markets. Getting there meant abandoning a horizontal idea that sounded smart, living in customer discovery until the real problem showed up, and learning that 90% of the people you reach out to won't answer. He's an introvert who sends the messages anyway. He survived the pressure of a 16 week accelerator, a demo day in front of 500 investors, and a lesson about building for regulated industries that he wishes he'd learned a year sooner. If you're a technical founder trying to figure out product market fit, or any founder who's ever mistaken a finished product for a validated one, you'll recognize yourself in the mess.
1️⃣ A Great Product Is Not a Business
Yasith had working tech and a YC interview, and the feedback was blunt. A good technical product isn't a business without a specific use case. If you build first and ask later, you'll spend months polishing something nobody's waiting for. Pick one buyer and one painful problem, then prove it matters before you write another line of code.
2️⃣ Nice Feedback Will Cost You Months
Most people are too polite to tell you your idea isn't landing, and that's exactly why Yasith loves critical feedback. It's rare, and going without it means you keep building the wrong thing while your time and money run out. Ask for the hard truth, then thank the person who gives it to you. Kindness sometimes sounds like telling a friend there's something in their teeth.
3️⃣ 90% Won't Reply. Send the Message Anyway.
Yasith is a self-described introvert, and reaching out to strangers is hard for him. He does it anyway, because the few who say yes become advisors, early customers, and regular check ins. Your alumni network, your second degree connections on LinkedIn, and fellow founders are easier doors to knock on than you think. Wait until it feels comfortable and someone else will have the conversation first.
Timestamps
00:00 He left Google, Meta, and Amazon to build from scratch
01:15 Why he finally stopped experimenting on the side and went all in
03:12 The first idea that sounded smart and had no clear buyer
04:12 The harsh YC feedback every technical founder needs to hear
05:15 What it feels like to wake up and realize you're on your own
07:37 Wearing every hat and wondering if you'll survive it
08:45 Inside demo day: 14 startups, 500 investors, five minutes
11:15 How an accelerator coaches you to pitch better than you think you can
13:12 How customer conversations quietly rewired the product
14:12 Why financial firms want AI but can't touch ChatGPT
17:52 Why he actually loves harsh feedback
19:31 What to steal from Google and Meta when you're building alone
20:44 Why playing it safe will sink your startup
22:14 The best advice he's gotten: talk to more people
23:03 Where to find customers when you have no audience yet
25:04 The introvert's guide to reaching out when it feels awful
26:56 Why founders say yes when another founder asks for help
29:27 The unlock he wishes he'd found a year sooner
34:18 What success actually means to him
38:39 The realistic goal for next year, and why 10 clients would be a win
43:05 Don't lose your optimism, and stop solving the wrong problem
Follow Yasith to watch a founder who loves hard feedback build Quantuma in real time.