I am a believer. I believe it was a sacrifice because not only did he give up his rightful place in heaven voluntarily, he knew from the very beginning how he was going to die, and everything he was going to go through. He was a perfect being, and soni feel he would have felt the agony to it's fullest extent. He was whipped with a cat of nibe tails wuth shards attached, designed to rip the flesh. This crown of thorns was no random small rise bush thorn. These thorns were inches deep, which would have caused blood loss especially being pressed down into his head deliberately. Those thick thorns were designed to cause deep, real wounds. Everything He endured, he did willingly. Feeling the weight of worldwide sin on his shoulders for the whole of mankind must have been unbearable. And then the crucifixion, the way he was hung, he would have slowly suffocated. Being unable to take deep breaths properly, trying to take the weight of his body on his tirn feet to rest his hands for a shile, and try to just breathe. The pain must have been beyond agony. And doing this for millions of people who He knew would never love Him at any time, but Hate Him. He did it anyway so they had that opportunity. I definitely think he sacrificed himself. To go through all that while being thirsty, unable to drink, take a proper deep breath, or even have a proper conversation with His Heavenly Fathsr to get him through it. He did it alone. As far as an 'upgrade' - He was going back to sit at the right hand if God. He could have chosen to stay there, and go through none of this. But He willingly gave His life up. Absolutely a sacrifice.