Just like "nationalism", the word "capitalism" has a really negative connotation nowadays. I bet that when you read that word, you immediately got some negative feelings about it.
The word "capitalism" immediately spawns thought of greedy and abusive huge megacorporations invading every market, screwing up both customers and competition, caring very little if at all about customers' rights, and which will go to any lengths necessary to make profit. They also elicit the mental image of these megacorporations going to foreign countries to abuse and deplete their natural resources and to employ cheap local labor in horrendous working conditions for a minimal salary. The word "capitalist" also spawns the thought of the greedy industrialist who abuses his workers, treating them almost like low-paid slaves. Both words also give mental pictures of huge wealth gaps between the extremely small rich majority, and the poor majority, many of them who live in extreme poverty, even on the street, with nobody caring about them (especially not the megacorporations.)
In other words, "capitalism" has pretty much become a synonym for "anarcho-capitalism" (in other words, capitalism that's completely unrestricted by governmental control and limitations, which means, effectively, that the megacorporations regulate themselves, as there is no higher authority imposing limits and sanctions to their actions.)
The thing is, we often tend to judge something based only on the most visible extremes, rather than seeing the bulk majority of it. Those abusive megacorporations do indeed exist, but they form a really, really small minority of the total body of the worldwide capitalist market and economy. They are the extreme form of it.
Moreover, when the word "capitalism" is uttered, most people think of only one single country: The United States. Most people seem to forget that capitalism is really widespread, and most countries have a form of capitalist economy.
The thing is, in most countries the capitalist economy is strictly regulated by a strong government. And that's exactly how it should be. The government makes sure that capitalist megacorporations do not get out of hand, nor start abusing the citizens for their own profit. The government imposes customers' and workers' rights, and puts limits on commercial abuse (such as deceptive marketing, anti-competitive conduct, fraud, monopolies, and so on.)
The fact is that without capitalism, we wouldn't have the level of technological progress that we today have. I find it quite ironic how so many people attack capitalism... by using computers and technology that are a direct result of capitalism.
Sure, capitalism is at its core greedy. But this "greed" is what drives technological innovation. It's what drives corporations to become market leaders by improving their products to be better than the competition. There's a constant race between corporations on who makes the fastest, smallest and most efficient piece of any particular technology. We wouldn't have the desktop supercomputers we have if it weren't for this competition. And the competition is directly caused by, to put it bluntly, greed.
Greed is generally a negative trait. But in this particular case, it really isn't. Sure, it can sometimes lead to abuse and skewing of human rights, but it has also lead to amazing technological advance. And capitalism is the most effective form of economy that entices this.
Is capitalism perfect? Of course it's not. However, capitalism, when tightly controlled by a strong government, is the best form of economy that there seems to exist. Many countries have tried many different forms of economy during history, but (government-controlled) capitalism just works the best, like it or not. You wouldn't be reading this text if it weren't for capitalism.
Remember that the United States is not the only country in the world. There exist other countries as well, and many of them are quite developed welfare societies regardless of their capitalist economy.
(Curiously, "capitalism" has become such a dirty word that even many people who live in these countries deny them being "capitalist". It's like it would be shameful to say such a thing. But there is no way around it: They are capitalist countries, and they are doing well. Capitalism just works. No need to be ashamed of it.)