In the Namek arc, Vegeta reveals to Goku while dying at the hands of Frieza the truth behind Planet Vegeta's (Saiyan planet) destruction, that it was Frieza who destroyed the planet. Goku, although still hating both Vegeta and the Saiyans, couldn't help but respect Vegeta for crying and begging to him, because of how hard it must've been for someone as prideful as Vegeta to do it. It was a level of pride Goku can relate to being a Saiyan himself, because it wasn't Vegeta liking the Saiyans which Goku can never do that filled his emotions, but it was how the Saiyans were the source of Vegeta's own pride, of what he is. And although Goku has opposing beliefs to Vegeta, he wanted to share Vegeta's pride out of respect. Meaning, taking pride in himself and his own beliefs as a Saiyan raised on earth. That's why Goku choose to fight for the Saiyans, because Frieza enslaving the Saiyans was an insult to what Goku is. This marked Goku's full acceptance of who he is to the point that he's willing to defend it.
During the fight with Frieza, Frieza pointed out how hypocritical it is to fight for the Saiyans despite how evil they are. With Goku responding with that's what led to their demise. This showed that although Goku was willing to defend the Saiyans, he's still doesn't defend them based on how right or wrong they are, but by what they actually are. Goku himself still believes being a Saiyan can led to him doing wrong things, but still accepted it rather than trying to defend how right it is to do it.
Goku believed his presence was creating real danger for those he loves hence why he decided to stay dead, which was him finding an equilibrium between his desire to fight vs his desire to protect the earth which he was only able to do by accepting himself like he did in the Saiyan arc. If he continued to celebrate what he is (after King Kai told him in the Saiyan arc) by being overly proud of the perks being a Saiyan provided, he would've ignored his limitations due to his proudness and ended up thinking he doesn't need to stay dead and can happily defend against any strong threats that shows up. If he continued to loath what he is (After Radtiz told him) he would've referred to himself only as an earthling and not own up to what he is which would've lead to him not thinking too much on his limitations by ignoring what being a Saiyans means for him, leading to him not thinking the earth is better off without him. Accepting himself like he did was the result of his purity that was strengthened throughout his arc, the purity that is the central point of who he is no matter how much it conflicts with his feelings. His pure desire to fight.
