Is it permissible to practice writing professionally after discovering the talent through using neighbors' internet without their knowledge, and can one give charity on their behalf for each book as an expiation?

Using a service owned by another is forbidden because it is consuming people's wealth unlawfully and an infringement on the rights of the neighbor. The Qur’an and Sunnah have emphasized the rights of the neighbor and the cessation of harm to them. One must repent and seek forgiveness from the neighbors or pay them compensation. If seeking forgiveness would lead to greater harm, then there is no objection to paying compensation through stratagem. Material gains from work and authorship in beneficial fields are permissible.