good luck vs happy chance

good luck and happy chance both are nouns.

Word	Noun	Adjective	Verb	Adverb
good luck	Yes	No	No	No
happy chance	Yes	No	No	No

As nouns, good luck and happy chance are synonyms defined as:

Other synonyms of good luck include break.

good luck (noun)	happy chance (noun)
an unexpected piece of good luck	an unexpected piece of good luck
a stroke of luck
an auspicious state resulting from favorable outcomes