First of all, there are a couple of things we need to get you straightened out on. People are certainly not afraid to spend money because they may lose their jobs. I don't know of anyone who has ever been fired from their job for spending their own money. People may lose their jobs, so they are afraid to spend money.
The next thing is; demand doesn't drop because money isn't spent. Money isn't spend, therefore there is less demand. People do lose jobs because demand drops. But this demand thing, goes back to what we said in the previous point, people may lose their jobs, so they are afraid to spend money. Finally, you asked how is this Obama's fault? Well...
That comes about as a result of him being elected president. You see, in this country, we elect a president who has certain skill sets and ideas, because we intend to hold them accountable. If we didn't hold presidents accountable and nothing was ever their fault, we wouldn't need to elect them as we do, we could just do an online poll of the most popular celebrity, and appoint them president for life. So, since we elected Barack Obama, and he ran on the promise of his "Hope and Change" idea, turning the economy around and bringing us out of a recession, and since that did not work, and instead, failed on ice... then we have to hold Obama accountable for his idea failing.
Back to the problem of people worrying they may lose their jobs... Seems like Obama might do something to reassure people they wouldn't lose jobs, like maybe he could do something to help small businesses, or even big corporations? Maybe he could get his Atty. General to stop relentlessly suing capitalists and his Democrat Congress to stop hauling them before hearings? Maybe Obama could get the left to shut up with the War on the Rich bullshit, for at least a few years, until we can dig out of the hole? The way I see it, there is a helluva lot Obama COULD be doing, that he's not. And why should he? With brilliants minds such as yours, ready to give him a pass on everything?