The real reason why bitcoin is invented is to make it as a real currency like dollar and euro but since majority of the people are making it as a good investment and never really use it in most of their payments, so bitcoin remains as an alternative currency next to fiat. Crypto will gain more recognition in the next years but replacing fiat for crypto is still very impossible for now to happen.
Actually it's fine if bitcoin is being used for investment. There are many people out there who invest to fiat for example USD and Euro but the problem which bitcoin faces is the fact that most of people who use bitcoin prefer to use it as an investment rather than spending it and I can see that people who truly use it for making an online transaction is quite few compared to majority of bitcoin users meanwhile those fiat investors are only minority.