Bearded Yetis have lived in hand dug caves for thousands of years and past down through the generations special tools to carry out the task.
This diamond pickaxe is a bit OP with its fortune enchant at 20 and efficiency 5 but it has no unbreaking enchant to keep it from giving an infinite advantage. So it will eventually get worn out and need to be repaired and in time become to expensive to keep. It should only be given as a prize for a server contest.