Daily Chinese Idiom Guessing Game
Not worth being surprised; not at all surprising.
足值得。不值得奇怪。指某种事物或现象很平常，没有什么奇怪的。
宋·毕仲游《祭范德孺文》人乐其大而忘其私，不然则公不足为奇。”
Given his experience, his success is not surprising.