hello, i believe most men want to donate because of their strong,natural instincts to ‘spread their seed’.
most sprem donors claim to want to help out and ‘give the gift of life’ to women with no apparent recompense ,and perhaps some do, but it’s a fact that it’s hard-wired into a mans nature to seek to fertilise as many women as possible.
DR Robert Winston (well known expert in human fertility) described this fact with a comparison between human males and thier nearest primmate counterparts i.e gorilla and chimpanzee.
He said that ,surprisingly, a gorilla has smaller testicles than a human and a chimpanzee has larger testicles than human or gorilla. This is because a gorilla has only one or two sex partners so he only needs small testicles, where as a chimpanzee has many more sex partners and thus needs more on-demand sperm and the same is true of men. Larger testicles=larger amount of sought after sex partners. The act of mixing or joining sperm and eggs Whether by A.I or any other means is SEX (as far as nature is concerned).
So the male donors are indirectly fertilising women and that is the Desire the recompense, the reason why.
some may think that’s wrong, that’s why some claim compassion and charity motivates them to donate. But it seems to be natures way.