We can't stop wondering how people could vote plainly against
their economic interests. What is so moral about the choice to be unemployed or greatly underpaid?
Nevertheless, here is a guess why people voted like that. Perhaps republicans stealthily countered the economic argument by the neo-calvinistic "truth" that you cannot do much about affecting people's economic position. To put it (very) roughly, it says that God awards winners and punishes loosers. So if you are poor, it's your own falt, you do not deserve to be beter off. If you are rich, that's the wish of God, you should do your best to get even more rich.
From this point of view, any economy "manipulation" or "artificial" involment in wealth distribution is against God's will. It is like manipulating DNA or brain cells, that is, like picking God's job. That might be a reason why people do not care much about Bush's competence in economy and social security (and similarly, in international or environment matters). In this sense, Bush is "really" God's chosen man - he does not go into God's business. If people are religous in this way, they are not ready to accept the idea that economic future (or international relations, environment fate) are in politician's hands. And certainly they would hardly believe that these things are in their hands (sometimes).
So while rational people may be afraid that Bush's policies will lead to certain disasters, other people do not think that they should worry about that (either because God won't be that cruel, or that he is always right with his decisions). Trying to do something about declining economy, environment or international relations is something of a herecy, it may seem...