Microsoft is an USA company, and its success is great for the American economy.
But if you don't live in the USA, when you buy propietary software (eg Windows), about a half of the money goes directly to the software company's HQ (eg Microsoft's): that money leaves your country, while the other half stays in (sales commissions, etc.: no technical benefits). Your country is not producing anything, and you don't even need qualified people to sell boxes. That leads to IT professionals with no high level knowledge who only install and configure proprietary software without the option of modifying/learning/customizing it.
With Free Software (eg Linux), the economy (and IT professionals' knowledge) of your country could improve, since there could be a lot of small/medium companies customizing solutions, providing support, consulting, etc.
People who know how to do things and retain money in your country will benefit from it, rather than people who just sell boxes with a predefined sales pitch, sending your money offshore, leaving IT professionals without real knowledge about how things work.