'King of Side Hustles' Chris Koerner Shares How to Reach $10K Monthly Income Without Quitting Your Job

Serial entrepreneur Chris Koerner told Steven Bartlett on The Diary of a CEO that 90% of his business ideas can be launched with £400 ($500) or less, and none require leaving full-time employment.

Koerner, 38, has started more than 80 businesses since selling golf balls outside his home in Utah at age nine. His ventures have collectively generated low hundreds of millions in revenue and low tens of millions in profit, though the majority have failed or been abandoned.

'There's enough time in the day to do these on the nights and weekends,' Koerner said in the interview, which aired on 8 December 2025. 'Try to give me an idea where you have to raise money, or where you have to go all in, or where you have to quit your job. It doesn't exist.'

Koerner's £400 Side Hustle Ideas Shared on Diary of a CEO

In a segment where Bartlett handed Koerner three suitcases containing £400 ($500), £800 ($1,000), and £4,000 ($5,000), Koerner outlined specific businesses for each budget.

His top pick at the £400 level was an AI implementation service for small businesses. He cited figures suggesting 400 million small businesses exist globally, 77% of which say AI would be transformational but only 5% use it meaningfully.

'I will make your business more money or save your business money with AI,' Koerner said of his pitch to potential clients. 'I'm going to use fifth-grade words. I'm not going to use LLM. I'm not even going to say ChatGPT.'

He said the pricing model ranges from £400 to £4,000 ($500 to $5,000) upfront, with a recurring monthly fee of 20% of that amount for ongoing maintenance.

Other £400-level ideas included drop servicing - creating a website for a trade business, generating leads through ads and subcontracting work to local operators - as well as niche directory websites and used vending machines.

Scaling Side Hustles to £8,000 a Month

At the £800 ($1,000) level, Koerner recommended wedding rentals and local email newsletters. He described a case where someone built a wedding arch from timber for £160 to £240 ($200 to $300) and rents it at £800 ($1,000) per event through wedding planners. About 75% of weddings now take place outdoors, he said.

For the newsletter model, he suggested spending the full £800 on Facebook advertising to acquire roughly 1,000 local email subscribers, then monetising through sponsorships from local businesses at approximately £0.40 ($0.50) per subscriber per month.

At the £4,000 ($5,000) level, Koerner pointed to small RV parks as his most profitable venture. He has been involved with about 35 parks over seven years, generating £2.4 million to £3.2 million ($3 million to $4 million) in annual revenue. Small parks with three to 10 sites are three to 10 times more profitable than single-family rental properties, he said.

Koerner on Copying, Passion and the Risks of Side Hustles

Koerner told Bartlett he favours copying existing business models over innovating at the outset. He cited an example from 2010 when someone offered to buy broken iPhone screens from his phone repair business for £2.40 ($3) each. Rather than sell, he replicated the buyer's remanufacturing model, found suppliers on Alibaba and scaled to £7.2 million ($9 million) in revenue within three years.

'I don't assume that other competitors are idiots,' he said. 'I've been proven wrong too many times.'

On passion, he was blunt. 'Follow the profit until you can afford to follow your passion,' he said. He also cautioned that entrepreneurship is not the escape many assume. 'Many of the people that think they want to be an entrepreneur, they just like the idea of it. Entrepreneurship is not a solution. You're trading something for it.'

Koerner identified two macro trends he believes present the largest current opportunities: implementing AI into existing small businesses and acquiring businesses from retiring baby boomers, with 10,000 retiring daily in the United States.

He has over one million followers across social media and hosts The Koerner Office Podcast.