It depends on your perception of spoilt. It is a popular misconception that children who have wealthy parents are spoilt. It is important to establish that there is a difference between having nice things and being spoilt.

Willow Smith, I'm sure, will have almost anything she wants, but this does not necessarily mean that she is spoilt.

Sharpay is the most spoilt

Oh, the rain spoilt your game.

"Spoilt" means somehow ruined as in the sense of gone rotten.

The sentence "The furniture has spoilt" is not right, spoilt is not a word. Spoiled is acceptable, though the sentence works better as "The furniture has been spoiled".