Yes, WEALTH is a Scrabble word!

Letter values in Scrabble US: W 4, E 1, A 1, L 1, T 1, H 4.

Is it a valid word?

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

the state of being rich and affluent; having a plentiful supply of material goods and money
the quality of profuse abundance
an abundance of material possessions and resources
property that has economic utility: a monetary value or an exchange value