They only seize possessions that were substantially or directly used in the commission of the crime. So a house would be seized if it was used as a meth lab. A car would be seized if used to transport drugs, etc.
That is separate from a fine imposed during sentencing, though. Like that piracy notice before movies, 5 years and $250,000 fine.
This is where assets may have to be liquidated regardless of their connection to the crime.