Performs better than fiat currency in terms of price, but not in terms of adoption, price stability, utility. This make Bitcoin closer to assets like gold than a currency for regular use.
Bitcoin perform the role that other currencies can not serve any purpose, take for example if you leave and saved your money in your local bank currencies and it happens that you traveled to another country you may have problem with apending your money and tou bank savings may become useless and the only option will be Bitcoin as the only alternative.
It may be nice to have you currency also act as an investment, but the best way to store your wealth is in a diversified portoflio of different asset types - stocks, bonds, gold, bitcoin, real estate, foreign currency and so on. It's not a great idea to have a million dollars in your bank account and just watch it getting eaten by inflation, but it's also not a smart move to put it all in Bitcoin and risk losing a big portion of it. Don't put all your eggs into one basket.