In fact no one needed an iPhone when it was released on the market. People needed a mobile and the possibility to access the internet whereever they are. The iPhone just fulfilled their needs in one device.
When looking at bitcoin it might not be obvious why paying with it is the better solution. The point is while bitcoin as a currency fulfills the same purpose as any other form of payment it has ideological benefits. In a time where technology enables banks to track payments everywhere, where you get personalized ads based on your purchases and whatnot it's important to have a decentralized payment system. No central authority can associate your money directly to you, you're independent of the solvency of your country (atm this is a big plus!) and therefor your country can't come and seize your funds for the failure of their politics.
Of course, our existing monetary system might be super easy to use. The normal user might be used to the system in place and doesn't jump on it right now. You won't find any revolutionary movements in our developped countries anymore. For bitcoin to evolve it will slowly need to increase its usabilty. When the time is right and that might be when the next financial crisis comes, the use of bitcoin or any decentralized cryptocurrency in general will show its true advantages. And you can jump on that train either after you lost all your fiat in the next crisis or you can now at least consider the possibility cryptocurrency is a solution to our defunctional banking system and get used to it.