REUTERS/Pascal Rossignol

For Mike Hirschkorn, there's a simple, harsh reality when it comes to making sales: Amazon is a "necessary evil." Hirschkorn oversees the U.K. operations of Gorilla Sports, a German-headquartered online retailer that sells sports equipment like free weights and cardio machines. He said roughly half of the company's U.K. sales come via Amazon.com. "Basically if you're an online retailer in the U.K. you have no choice," Hirschkorn told CNBC's Beyond The Valley. "If you don't sell on Amazon, you don't have a big business." Retailers like Gorilla Sports rely on big e-commerce firms to get their products in front eager consumers seeking convenience and affordable prices. The difference, according to Hirschkorn, is a customer base of a "few hundred" or "few thousand" locally versus "millions" with Amazon.

But the visibility and accessibility big tech companies give to smaller businesses around the world come at a price. Hirschkorn said Amazon takes an 18 percent cut, including VAT, of the sale of each product, which he calls a "very hefty chunk" in a business with slim margins. The company has tried to shift sales away from Amazon to its own website, but soon discovered it went from paying one tech giant to another. "It used to be that we were very keen to drive traffic from Amazon to the website because each sale was cheaper, but now we're spending almost as much as a percentage of our sales advertising on Google as we would be paying fees to Amazon," Hirschkorn said. "Either way one of the big Silicon Valley companies is going to win." "We spend billions of dollars each year to help our selling partners succeed in our store, driving traffic, operating the servers and infrastructure that keep our online store open at all times, and combating fraud and abuse. Our biggest single capital expenditure is our fulfillment and distribution network, which directly benefits our selling partners, who now have as many units in that network as Amazon itself," a spokesperson for Amazon told CNBC via email. "Our investments allow our selling partners to focus on their products while reaching customers throughout the world, leveling the playing field and lowering entry barriers. Today, our selling partners are outperforming Amazon retail -- they have grown from zero to 52% of paid units sold, and continue to grow twice as fast as Amazon's own sales," the spokesperson further added. Google did not respond to CNBC's request for comment.

Either way one of the big Silicon Valley companies is going to win. Mike Hirschkorn Gorilla Sports U.K. Director

Consultancy PwC found 59 percent of the people polled in its Global Consumer Insights Survey shopped online at Amazon, JD.com or Alibaba's TMall in 2018. Amazon sold more than 100 million products during its big "Prime Day" event last year, while Alibaba racked up more than $30 billion in sales from its "Singles Day" event alone. Many small retailers have no choice but to use Amazon or Alibaba, and reluctantly agree to those platforms' terms and conditions.

Never a greater time for small businesses