That's a fairly simplistic view. Let's say I own a company making widgets and selling them for $5. Materials cost me $1 and labor costs me $4 per widget, so I make about a dollar profit. Then CheapChinaCorp comes onto the scene and says "Hey, all you're doing is making widgets. I can make widgets for cheaper!", and they start pumping out widgets. Materials still cost $1, but their labor only costs $1 as well, so they sell theres for $3. Now basically *everyone* will go to whatever store, look at Widget A from USACorp for $5, and Widget B from CheapChinaCorp for $3, and buy the latter.
Now I could try to lower wages, but minimum wage puts a floor on that, so if they can pay their employees less than minimum wage (and they can!), I can't compete on cost. So I move my factory to Mexico before I go out of business, now my labor cost is only $1 too, and I'm still in business! Yeahy!
You can't think of it as "Giant mega corp" has 5000 jobs that they can bestow on whoever they feel. Companies have to make money, or they go out of business pretty damn quick.
There is also a flip-side to shipping manufacturing overseas. Let's say you're a consumer who also works in a dvd player factory with 100 other people. You happen to have a monopoly for the moment. You produce DVD players that cost $500 in order to pay you and your coworkers $20/hr. CheapChinaCorp comes onto the seen and releases a $100 DVD player. From a nation-wide perspective, is it better that everyone spends an extra $400 to keep you 100 people employed, or that everyone has an extra $400 in their pocket for other expenses? Which is a better "value" to the country?