Because they support (extreme) laissez-faire politics - even though the vast majority of tea party members don't understand the term or its political, economic and social implications. The political naivety shown by these people is truly breath-taking. They do not - for instance - understand that the policies they are supporting are not in their own interests; but the interests of the corporatocracy. They think they are campaigning for 'freedom' (another term they seem to have problems with) when all they will get is enslavement by the rich. These people are supporting their own impoverishment.
It 's quite frightening when you think about it. The last time a nation was so totally 'sold' on a political ideology detrimental to the interests of the general populace occurred in the 1930s in Nazi Germany.
Mussolini himself declared that facism should, more accurately, be called corporatism.