Swarth ( selfishness ) generally considered a negative tendency in Sansar, becomes a positive tendency on the path of spirituality.
If you try to understand the meaning of Swarth,
Swa = Self
Arth= Benefit
Here “Self” is your true self – the soul, the consciousness.
By constantly staying in pursuit of the self, one needs to be self-ish and start steering away from misguiding, misleading, and most of the times, unnecessary involvements of Sansar that distract you away from the SELF.
Think of the SELF first.
Only Swarth can lead you to Parmarth ( param = others, arth=benefit ).
An act of Parmarth performed without knowing the Swa ( self ) cannot be genuine.
Go from Somebodiness, to Nobodiness and finally to Everybodiness.