What does this quote mean?

In Gandalf’s final speech to Bilbo, he says the following: “Surely you don’t disbelieve
the prophecies because you had a hand in bringing them about yourself? You don’t really
suppose, do you, that all your adventures and escapes were managed by mere luck, just
for your sole benefit?” (p.330). What do you think Gandalf is saying in this quote? Was
there any luck in Bilbo’s success?