its not that the holocaust is exagerated. that would be more what they call "holocaust denial" than the Holocaust Industry.
the Holocaust Industry generally refers to the groups of people that exploit Jewish suffering and the Holocaust to build their own institutions and further their own agendas. this could be anyone from the World Jewish Congress, to the Anti Defamation League, to the state of Israel.
using the term "Holocaust Industry" most of the time is used by people who are concerned that something extremley painful and horrid (the Nazi holocaust) is being used in a cynical way, or in a way that might diminish its seriousness.
thats the basic premise of Finkelstein's book. in his chapters on holocaust researchers i think he comes off alot weaker than when he details how the Swiss Banks were shaken down for money that holocaust survivors didn't see alot of the benefit (it went to the institutions that are built up around it).