Nice guys do not necessarily finish last.
In reality, being nice is a factor to success that can go both ways.
The crucial factors include talent and timing. Timing may be a factor that nice can contribute, but ultimately, your talent level will give you a better chance to determine your actual chances of being the chosen one in the end.
You could have great talent, but your particular gatekeeper is looking for that near-perfect personality trait. Is it sell your mother to secure the opportunity? Is it the animate approach to beat down the opposition?
Is it just a generally nice and polite person, aware of their surroundings and unwilling to commit acts that would embarrass their grandmothers?
Nice guys finish last is a saying meant to convince those who may be hesitant to take a chance if it means doing battle with someone not-so-nice. It is never them being nice that is the holdup. Nasty guys can finish just as poorly if the gatekeeper of the moment wants to make that choice.