"I'd say to Dustin that 'you've got an enormous future in the game. You've got terrific talent'," Demetriou told Seven's Talking Footy program on Monday night.
"'You've got good people at this football club who have been doing the right thing by you and they've invested a lot of time in you and you should make the most of your opportunity'.
"It's a shame because everyone knows he's got ability."
The young midfielder was suspended for two games by the Tigers last year after sleeping in and missing a training session.
The Tigers on Monday expressed their extreme disappointment that after months of negotiation and their belief they had been close to a new deal, Martin and his management had told them he was considering other options.
"Given the considerable effort we have put into Dustin's development, both on and off the field, and our efforts to retain him all season, we are extremely disappointed with this decision," Richmond's football manager Dan Richardson said.
Martin at one stage lived with club president Gary March.
The Tigers feel the 22-year-old, who was selected with the club's No.3 NAB AFL Draft pick in 2009, has been given extensive assistance to help his on-field and off-field development.
Richardson hinted Martin's unwillingness to re-sign was all about money.
But Demetriou warned Martin: "Don't waste the opportunity that you've got.
"If you're not prepared to commit to the club, commit to the team … they've looked after him a lot, some clubs aren't prepared to take that risk," he added.
Melbourne and Greater Western Sydney have expressed interest in Martin, although North Melbourne's dual premiership skipper Wayne Carey says Martin's manager Ralph Carr might be over-reaching with his financial demands on behalf of his client.
"If Ralph has his best interests at heart, (they should) walk back into the Richmond Football Club now and be the bigger people," Carey said.
Former Western Bulldogs ruckman Luke Darcy says it will be interesting to see the type of offers Martin attracts from rival clubs.
"I'm not convinced that he's going to get the offers that his manager thinks," Darcy said.