Idle Complaint
Grumble
noun
A foolish and stupid person will make lots of idle complaints. You really don't like being around them because they grumble about how nothing is good enough all the time. But they really just don't get it.
ぐち
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
愚痴ばかり言っても、何も変わらないよ。
If you only talk of idle complaints, nothing will change.