According to ProFootballTalk.com, the amount that Albert Haynesworth would get fined by the Washington Redskins could add up quickly:

For now, the Redskins can fine him roughly $10,000 for skipping the minicamp.  If he stays out when training camp rolls around, the number increases to more than $16,000 per day. They also likely will be able to pursue a portion of his signing bonus.  

So by the end of the training camp season, the amount of cash that Haynesworth stands to lose could be in the hundreds of thousands, not even including any portion of his signing bonus that he would have to return. Albert had to do this math before he pulled this move, so it must be worth it to him.