Gadgets and Credits

Always wondering why people bother to buy those new gadgets every time they have new models come to the market. Maybe they just want to follow the trend. I would not mind if they really have budget for that. But I know some people that are willing to get those gadgets by using credits. Is it really wise to do like that? They don't really calculate the interest that they need to pay for those things which I believe are categorized as secondary things in life.