The 30-year-old has fallen out of favour under coach Zinedine Zidane and almost left the club last summer, but a move to China fell through and his future remains uncertain.
“As I’ve always said, he’s quite happy in Madrid,” Jonathan Barnett told BBC Radio 4’s Today programme.
“He has a very nice lifestyle. I don’t see why he doesn’t see his career out at Madrid probably.
“It’s his life that he wants to lead. Financially, he will want for nothing the rest of his life, and his children and grandchildren."
Bale recently expressed an interest in playing in the United States, but Barnett believes a possible return to the Premier League is unlikely for his client.
“He’s won nearly everything in the world, except the World Cup, but unfortunately he plays for Wales so some things are beyond him," he said.
“So he’s won everything else, to come back and play [in the Premier League] would be unbelievable – a big thing.
“I don’t think he wants to do that at the moment. He’s quite happy to play at Real Madrid.”
Bale's current contract at the Santiago Bernabeu is up in 2022.