yes, why not.

This.

And also because the world is overpopulated, I kinda don't want to help bring another baby to this life, I prefer adopting an already existing child

No.

Yes, gotta help the good lesbian sistrens out there

but it's kinda messed up if people use too many of your sperm and create thousands of kids, an incest mess that would become if these kids fall in love without knowing they're related

A friend of mine who has had a huge crush on me for like 5 years (poor sis doesn't know I don't swing that way) asked the other day if I would give her my sperm in the future so she could have my baby

I don't want to have children ever but I don't like the idea of having a child that I know nothing about. Yet I would really like to help a same sex couple have a baby now that I think about it... so idk I would have to think about it as I get older and older I guess.