Spurs are pushing for a top-four finish in the Premier League, along with London rivals Arsenal and Chelsea, but Miller believes that the club don't have the financial means to sustain a place near the top of the table.
"We've got to remember we're talking about Tottenham," Miller told talkSPORT. "They bat far above their means. Manchester United make three times our turnover. Arsenal make two-and-a-half times our turnover and Man City and Chelsea make double.
"Today the game is all about money. It's about wages and buying players and Spurs are batting far above their average. As things stand in the Premier League Spurs shouldn't finish higher than fifth anyway because the finances suggest they shouldn't, but they have before.
"Apart from the top three clubs, everyone else, and that includes Arsenal, unless they're at full strength, struggle."
Spurs are currently in fifth place, two points adrift of Arsenal above them.