Bitcoin has power because its benefits and functionality are recognized by various parties and countries, safe and fast is one of the advantages bitcoin, at this time people need security and speed in the transaction, that's why bitcoin is needed today
I don't know why but it's functionality is not that much. Fast in transaction? I think that was years ago and bitcoin is not that used by the people so I think bitcoin is not that powerful as we know it, there are many people who don't know bitcoin, they are getting attracted to it's price that is why they use it. If bitcoin has power, I think bitcoin will be stopped by the government because it will be a thread to them. Also it has a good price so I think the bitcoin don't have the power but the fiat that you get when you sell your bitcoins.
Bitcoin does not rely on fiat. For now, it might be. But when fiat has crashed, bitcoin will not give a flying fuck since the prices can simply just be based on bitcoins instead. Bitcoin is still fast in transaction. Or at least it's relatively fast. When you're going to send money to someone, you'd have to go outside, and drive to the banks or some money transfer service. With bitcoin, you just have to increase the transaction fee and your transaction will be more prioritized than others, thus, having fast transactions. The people here talking about how slow bitcoin transaction is just don't put enough transaction fees.