Yes, YUPPIES is a Scrabble word!

Letter values in Scrabble US: Y 4, U 1, P 3, P 3, I 1, E 1, S 1.

Is it a valid word?

YUPPIES is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

a young upwardly mobile professional individual; a well-paid middle-class professional who works in a city and has a luxurious life style