"There's no question bosses work the lads hard, but the financial rewards are astonishing.
The band get very well paid, so they can hardly complain.
"They are easily (Cowell's company) Syco's biggest success story."
The group are set to go on hiatus in March following the conclusion of their latest tour and the upcoming release of album number five, Made in the AM, this November.
The CDs release date puts them head-to-head with pop star Justin Bieber, who will launch his latest pop offering on the same day.
An impending chart battle has sparked a public war-of-words between the two acts.
After the release, the One Direction boys are planning on starting their break with a holiday together.
"There's no doubt we'll see plenty of each other, we're gonna plan to go on a little lads' holiday," bandmember Louis Tomlinson told Good Morning Britain.
"Actually it's just the day to day things (I'll miss), we are like a family now, so it's the company that you're used to, it's like leaving school and leaving your friends behind."
- AP