The Bees were denied automatic promotion on a dramatic final day as Marcello Trotta missed a stoppage-time penalty against Doncaster, who duly broke down the other end of the field to score the goal that secured them the League One title and a place in the Championship next season.
Rosler's side must now put their agonising near-miss behind them as they face a two-legged semi-final against Swindon, but the manager is adamant they will bounce back from the heartbreak and prove their doubters wrong.
"A lot of people are writing us off now, but I don't see why," he told the Hounslow Chronicle. "That's a great motivational tool to use for the players.
"I've lived all my life to prove people wrong. My players have done that last year and again this time.
"We believe in the qualities we have. They have shown this season that they are capable of turning things around and playing under pressure."