Harry: Tough to keep top stars
His comments come as Spurs are enjoying arguably their best season since they lifted the league title 51 years ago.
The Londoners will go joint top of the Premier League on Saturday if they beat Wolves at home after putting pressure on favourites Manchester City, and rivals United, with a 2-0 win over Everton on Wednesday.
Roberto Mancini's men will have the chance to pull clear of the chasing pack again at Wigan on Monday, but a run of one defeat in their last 18 matches has left few doubting that Redknapp's squad have a real chance of challenging the Manchester duo for their first title since 1961.
But regardless of his team's ability to match the top clubs on the pitch, off it Redknapp concedes the likes of City, United and Chelsea are in a different league.
Spurs had to fight hard to fend off Chelsea's interest in Luka Modric last summer - when the Blues reportedly offered to triple the Croatian's wages - and Redknapp admits money, and not glory, is the prime motivation behind any top-flight footballer's thinking nowadays.
"Players play for a club and they enjoy being there, but if someone comes along and offers them a contract that could blow their current one out of the water, then you've got a problem," Redknapp said.
"I'd be talking rubbish if I said people wanted to stay at Tottenham just because we're playing good football. I'd be dreaming. If you want to keep the best players, we have to find a way of doing a deal that's near to what they can earn elsewhere, otherwise it will be a problem.
"If you're a top player and someone wants to give you a fantastic contract, it's very hard to hang on to them."
Spurs can breathe relatively easy for the rest of the season about Modric after Andre Villas-Boas confirmed he would not renew his interest in Modric this month.
But with the Croatian, Gareth Bale and Rafael van der Vaart all receiving rave reviews for their performances this term, the summer could prove the ultimate test of Spurs' ambitions of being regular title challengers.
Despite accepting it is part of the modern game, Redknapp laments players' desire to prioritise money over loyalty, and another aspect of the game which he dislikes is the role of agents.
The Spurs boss revealed on Friday that a representative of Jermain Defoe, who is not first-choice despite being the club's top scorer, has been complaining about his client's lack of game time.
He said: "Jermain Defoe changes his agent and the new one is ringing up saying: 'He's not playing... this club want him, that club want him'.
"That's how they make their money. By getting them a new contract somewhere. They take their cut and that's how it all works."
Aware that having a big squad will be key to ensuring Spurs maintain their title challenge, Redknapp is adamant that he will not let his fringe players, including Defoe, leave this month.
The first test of that policy came on Friday morning when Tottenham received an undisclosed bid from QPR for Steven Pienaar that was quickly rejected.
"I wouldn't want to let him go. He is a good player," Redknapp said.
"I don't have any need to weaken the squad. I would rather have a good squad for last 18 matches of the season than let one or two go who could play a part in the run-in."
Redknapp conceded that it would have been "beyond our wildest dreams" that his team would be within touching distance of the top of the table after their woeful start to the season.
The 64-year-old knows tougher fixtures lie ahead - Spurs face Arsenal, Liverpool and City within the few weeks - but also thinks that Mancini's men will suffer in the near future due to the absence of a number of key players.
Vincent Kompany is serving a four-match suspension, David Silva has ankle injury and Yaya Toure will be absent for up to a month representing Ivory Coast at the African Nations Cup.
"They are still a force but if you take Yaya Toure, Kompany and Silva out of your team, you're not going to be at the same level," said Redknapp, who takes his team to the Etihad Stadium next weekend.
"They are big losses for them."