The story of Joe Donor indeed raises many questions and ethical concerns. For one thing, the desire to become a parent is deeply personal, and in some cases individuals may resort to non-traditional methods to achieve this dream. In this context, Joe offers a service to those who, for various reasons, cannot or do not want to have children by conventional means.

On the other hand, Joe’s motivation to potentially have as many as 2,500 children raises important questions about parenting. Being a parent is not limited to giving birth, but also involves a long-term responsibility towards the child. One could argue that having so many children makes it nearly impossible for Joe to fulfill those parental obligations in any meaningful way.

Additionally, there are ethical implications regarding women who seek his help. As you mentioned, some reviews suggest that Joe might take advantage of vulnerable women. Although he apparently does not ask for financial compensation for his help, the fact that he asks them to pay his travel expenses could be interpreted as a form of financial transaction.

There are also health and safety implications. For example, concerns could arise about the transmission of sexually transmitted diseases or other genetic conditions.

Finally, there are also implications for the children themselves. As they grow older, they may have questions about their biological origin and knowing of the existence of hundreds, or even thousands, of half-siblings could be confusing and psychologically challenging.

In conclusion, while Joe’s choice to become a large-scale sperm donor may enable him to help those who wish to become parents, it also raises many complex ethical and practical questions.