The Corruption of Frodo

I don't know if this has been discussed at another time in the forums, but I have a question.

I understand totally what Gandalf was saying when he told Frodo in Moria that he was meant to have the Ring, but in the beginning, when Gandalf was in the Shire, he knew that the Ring had something to do when Bilbo got mad at Gandalf for telling him to leave the Ring behind, thus he knew that the Ring, in Frodo's hands would eventually corrupt Frodo as well. Why did he want to put Frodo through that?

Berserk