Neil Olshey
The first person that comes to mind when discussing someone who turned their back on the franchise and led Portland astray is probably former general manager Neil Olshey. His tenure as the Trail Blazers' GM had some successes, but he'll always be remembered for the failures.
Olshey drafted Damian Lillard after acquiring the sixth pick in the 2012 draft via the Gerald Wallace trade. He picked CJ McCollum despite the diminutive guard's size, age and experience only playing at the lower levels of the college game at Lehigh University.
But he also gave Meyers Leonard a contract extension worth $10 million a year when the center was coming off a breakout season - when he averaged 8 points and 5 rebounds.
That same offseason, he used the NBA's cap spike to splurge on mediocre players like Evan Turner. He signed McCollum to a massive extension and decided Jake Layman deserved one, too. Perhaps most confusingly, he matched Brooklyn’s offer sheet and re-signed Allen Crabbe to a four-year, $75 million extension.
Olshey's reign as Portland GM eventually came to an end in disgraceful fashion when he was fired after being found responsible for leading a toxic workplace environment.