Other usage of “家” preceded by modifying character(s): 专家 = specialist, expert 卖家 = seller 作家 = writer 商家 = businessman 人家 = other people perhaps relates to trades passed down through the generations.

大家好 = hi everyone 女士们先生们大家好=hello ladies and gentlemen nothing is 'big house good '

thanks!

大家 together means "all", "everyone". NOT "big house"