I'm sure there are people who just go out buying looking for specials and decide they need a memory card, so just pick one up along the way.
Or you could reason that it's unlikely that stuff on Black Friday will be more expensive than it is otherwise - useful if you can't be bothered following prices.

Consumerism is a big part of Western culture and economies - most people spend the large majority of their expendable income on consumption goods (as opposed to savings).
Do people know where their money is going?  Some yes, some no - probably explains why one of the most common financial advice (for those struggling, obviously) is budgeting.  I suppose devices like credit cards, lay-by loan schemes etc encourage this more.

On the other hand, money is there to provide you utility.  People will, thus, have different perceptions of what things are worth and be willing to spend different amounts on things.
Being an unemployed student, chances are your expendable income is close to 0, so you'll naturally be more conservative.  But if you're working and earning a decent income, it may make sense to splash out somewhat more extravagantly.

Personally, I'm rather difficult to impress and have a somewhat conservative personality, so I don't really feel the need to buy much.

(23/11/2012 01:48 PM)Tetris999 Wrote:  The expectations of a bad day?

In a relatively stable environment, not much.  In a less certain environment, one may be more willing to save.

(23/11/2012 01:48 PM)Tetris999 Wrote:  Do people think about optimizing their time and effort so that they get the most out of it?

A bit of a different question, but if I'm understanding you, it's usually difficult to do.

(23/11/2012 01:48 PM)Tetris999 Wrote:  Are people just buying things because they can? Or because someone told them to?

I don't think you can sum up all the reasons people buy things in such a simple statement, but I'd say those are certainly components.
I'd say people generally buy things because they ultimately provide (or hope to provide) utility in some form.

Congrats on the job!