just because some people don't pay their taxes when trading bitcoin and cryptocurrencies that doesn't mean bitcoin is affecting the economy of the whole country! these same people would never pay their taxes when they do other things so the economy didn't change because of them.
maybe bitcoin affects the world economy not in terms of income but in terms of convenience, for example there are many business people with international level that are very facilitated with bitcoin currency and how much progress in buying and selling using conventional currency is now starting to switch to bitcoin due to convenience , maybe something like this makes bitcoin play an important role in the world, especially the world of commerce.