Benitez will reunite with Liverpool when the Merseyside outfit visit his Newcastle United at St James' Park on Sunday.
The Spaniard enjoyed success during his six-year tenure at Anfield, guiding Liverpool to Champions League glory, while they narrowly missed out on the Premier League title in 2008-09 – finishing second to United.
Jurgen Klopp's Liverpool are among the contenders for this season's crown in their quest to end a 28-year drought but Benitez doubts the club's chances, believing the Reds need a miracle like Leicester City in 2015-16.
"When I arrived at Liverpool, the budget was £20m gross. When I left, it was £17m, but still people said I must win the title, I must compete," Benitez said.
"If other teams maybe aren’t doing too well, you can be there. We had 86 points one year and finished second. Why? Because United were there.
"Leicester won the title because three or four top sides were really bad and were not performing."
Benitez added: "[Manchester] United had around £50m more every year, but people said I had to compete against them every year. After, there was Chelsea.
"There are massive clubs with massive amounts of money and Liverpool were always a little bit behind.
"How can you win trophies? You have to create a good team with a great atmosphere and work hard and then you can get there.
"The reality is, the teams that have won the title, probably 90 per cent of the time, are the teams with the most money."
Liverpool are sixth in the table and eight points adrift of Manchester United and City, while Newcastle are two points further back.