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Teen Hustle to 0M+ Business

Teen Hustle to $100M+ Business

July 8, 2025 Victoria Sterling -Business Editor Business

From Teen hacker to Cybersecurity CEO:​ How Marcin Kleczynski Built a Multi-Hundred-Million-Dollar ‍Business‌ From ​a Side ⁤Hustle

Table of Contents

  • From Teen hacker to Cybersecurity CEO:​ How Marcin Kleczynski Built a Multi-Hundred-Million-Dollar ‍Business‌ From ​a Side ⁤Hustle
    • The Accidental Entrepreneur
    • From Bedroom Project to Global Cybersecurity Leader
    • Key⁣ Lessons Learned

It’s the⁢ era ‍of the side hustle and if you’ve ever considered starting ⁢one to earn some extra cash outside of your 9-5, ⁢you’re in ‌good company. These days, more⁣ than one-third of U.S. adults ‌have side ⁤hustles, and their supplemental gigs make an average of $891⁤ a month, according to recent research from Bankrate.‍ Of course, the most accomplished side-hustlers​ see much higher earnings, especially when they start a business that brings​ in nearly as much as – or substantially more than – their full-time ​sources of income.

Marcin Kleczynski, 35, is a Bay Area-based⁤ entrepreneur who was a teenager when⁢ he ​”unofficially” started the side hustle⁤ that would become a cybersecurity firm. Now the CEO of Malwarebytes, he⁤ and his co-founder ⁢Bruce Harrison ‌have ⁣grown the venture ⁤into a multi-hundred-million-dollar business.Responses⁤ have been edited for length and ⁤clarity.

The Accidental Entrepreneur

kleczynski’s story isn’t ⁣one of meticulously planned business ‍strategy. It began with a personal frustration – and ‌a knack for ‍problem-solving. “I was 13, and my computer ⁣got infected with a virus,” he recalls. “I spent days trying to remove it, and the tools available at‌ the time were… not great. They ‌frequently⁢ enough didn’t work, or they came ‌with their own set ⁣of problems.”

Driven by this experience, Kleczynski​ started tinkering. He wasn’t formally studying computer science yet, but he was a quick learner. He dove into online forums, read ‌everything he ⁤could find, ​and began experimenting with⁣ code. ​”I‌ started writing my own‍ little tools​ to clean⁣ up infections,” he explains. “It was ⁤a⁢ hobby, really. I was just trying ⁣to fix my own computer and⁣ help my friends.”

Word spread. ⁢Soon, people outside his immediate circle were asking for his​ help.‍ He began offering his services online, charging a small fee for removing⁣ viruses and cleaning up infected ‍machines.”It was very informal,” Kleczynski admits.”I ‌was ‍still in⁣ high school.​ I⁣ didn’t have a business plan or anything like that. It ⁢was just a way to earn some extra ⁤money and do something I enjoyed.”

From Bedroom Project to Global Cybersecurity Leader

What started as a⁤ teenage hobby ​gradually evolved into a legitimate business. Kleczynski continued to refine ⁢his tools​ and techniques, staying ahead of the ever-changing ​threat‍ landscape. He ​recognized​ a growing need for effective and affordable ⁢cybersecurity‌ solutions, especially for home users.

In 2008, he officially ⁣co-founded Malwarebytes with Bruce Harrison. “Bruce brought the business acumen and ‍operational experience that I⁤ lacked,” Kleczynski⁣ says. “He helped me turn my technical skills into a scalable business.”

The early ‍days were⁣ challenging. They bootstrapped ​the company, reinvesting every‍ dollar back into the business. They focused⁢ on building a strong reputation for quality and ⁤customer service.”We ⁣were obsessed with providing a great⁤ user experience,” ‌Kleczynski emphasizes. “We wanted​ to ​make cybersecurity accessible to everyone, not just tech ⁣experts.”

Their dedication paid‍ off. Malwarebytes gained​ a loyal following,⁢ and its reputation for⁤ effectiveness grew. The company expanded its‌ product line, adding new features⁢ and capabilities. ⁣Today, Malwarebytes protects millions of users worldwide from malware, viruses, and other online threats.

Key⁣ Lessons Learned

Kleczynski’s‌ journey from teenage hacker⁣ to⁤ cybersecurity ⁢CEO ⁣offers valuable lessons ⁣for aspiring entrepreneurs. ⁤Here ⁤are a few key takeaways:

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