Amazon just posted a massive beat on its bottom line.

That's not the number investors care about in the long run, says one trader.

"This is not an earnings story. It's about a growth story, and that's what people are betting on," David Seaburg, head of sales and trading at Cowen & Co., told CNBC's "Trading Nation" earlier Thursday ahead of earnings.

Amazon investors care more about the top-line growth than how well the company turns a profit, he said.

"I think the only thing the Street cares about with Amazon right now is that they have top-line acceleration," Seaburg said.

The e-commerce company fell short on that front in its second quarter. It reported 39 percent sales growth to $52.9 billion, falling short of the 41 percent increase analysts surveyed by FactSet had expected. Third-quarter guidance also came in short of estimates. It anticipates sales no higher than $57.5 billion, below the $58 billion targeted.

Amazon had blowout profit over the three months to June, though. Earnings of $5.07 a share were more than double estimates and more than 12 times the same period a year earlier.

"I'm not concerned about this story. I think from a long-term perspective you just close your eyes and buy any dips," he said. "This is definitely a long-term play."

Mark Tepper, president and CEO of Strategic Wealth Partners, is also bullish on Amazon.

"Amazon's a must-own in any portfolio, and we do like them ahead of their earnings," Tepper said on Thursday's "Trading Nation." "Company fundamentals look good; industry trends are strong."

Amazon's recent Prime Day, its annual sales event, also has Tepper confident in its business strategy.

"Prime Day was yet another success," said Tepper. "We're estimating $3.2 billion in revenues, up from $2.4 billion last year. They now have over 100 million Prime subscribers, and those Prime members are spending five times as much money with them."

Amazon said this year's Prime Day, which ran on July 16, was the best shopping event in its history.