独善其身
Better be alone than in ill company.
Solitude is better than ill company.
Keep one's distance.
Keep oneself to oneself.

eg：When making friends，you better remember that it is better alone than in ill company.

中英俚语俗语来源：孟子·尽心上：“穷则独善其身，达则兼善天下。”

反义词：于世沉浮 To drift with the stream.