He quit university to make YouTube videos and work at a hot dog stand.

Four years later, Swedish video gamer Felix Kjellberg, 25, made a staggering $US7.4 million in a year.

The extraordinary earnings - lodged by his company for 2014 and uncovered by a Swedish news site - are a rare insight into how much money is being made in the top tiers of YouTube stardom.

But not everyone is happy.

The YouTube mega-star, who goes by the name PewDiePie, has been forced to defend his massive earnings after the internet unleashed a torrent of abuse, saying he did not deserve his rewards.

PewDiePie became the most popular YouTube channel of all time in 2014, surpassing singer Rihanna's channel and garnering more subscribers than One Direction and Taylor Swift.

He records himself playing video games and uploads his reactions online, and has accumulated more than 4 billion views and 33 million subscribers.

The low-fi videos usually feature profuse swearing, crude jokes and shout-outs to his "Bro Army" fan base as he plays obscure indie video games.

However, on Wednesday he uploaded a video of a different kind, titled Let's Talk About Money, addressing the uncomfortable revelations about the $US7.4 million he earned last year.

YouTube forbids its stars from talking about their earnings publicly so the lodgings by Kjellberg's company, PewDiePie Productions, offered a rare insight into how much the biggest stars are making, Guardian tech reporter Stuart Dredge said.

In the six-minute video, Kjellberg said it was unfair for people to be angry.

"Whenever it comes out how much I made a certain year, people just get so shocked," he said. "They thought I just sit on my arse all day, and I just yell at the screen over here. Which is true. But there's so much more to it than that."

In 2011, Kjellberg quit an industrial economics degree at a Swedish university to focus on making YouTube videos.

He said he funded his early efforts by working at a hot dog stand and he never considered that it would explode the way it did.

He said he has donated more than $US1 million to charities, such as Save the Children and Charity:Water, but people only cared about how much he earns.

"It seems like the whole world cares more about how much money I make than I do myself," he said.

"I don't think there's any good reason why anyone should care, and on top of that I don't think there's any good reason why I should care either, so we're just going to end it there."

Tech experts said PewDiePie appeals to a demographic of teens and young adults who are very attractive to advertisers.

His videos, which have ads at the beginning and throughout, are being watched by almost double the population of Australia.

"As with many things, a few people at the top do exceptionally well but there's a long tail of people who don't make any money at all," Ian Maude from tech research firm Enders Analysis told the BBC.

"People have to see something special in you. It doesn't happen for everyone."