Bitcoin is not able to replace fiat, at least now. I believe that there will be another cryptocurrency which would be able to replace traditional money because Bitcoin has a lot of issues as well. BTC is good, but it is too far from perfect.
Btw, I totally agree that Bitcoin is not an investment. It was created for other goals. Greedy people don't get that

Well I do believe that bitcoin was created to oppose banks and corrupted governments. And yes, people now are seeing bitcoin as a source of money, and you cannot blame them. Most people need money. If their government does not give them the opportunity to work, then there are many other tools to get that done. Bitcoin has saved many people's lives. I do agree that some people are greedy but there also are people who are needy.