If everyone create their own currency and doesn't got a good features then it will be a dead coin, because the only one using it is only yourself, it is easy to create your own currency but it's hard to convince other to believe and used your coin, even if there are already people using your coin you still need to dedicate your time to make improvements and introduce your coin, so creating one coin won't make you less motivated
Yeah you're right. Everything will become useless if we have our own currency because you cannot use your own currency if they will accept it when use it to buy. And I think people will minimize the sins we did because popularly said money is the root of all evil. Imagine if we have our own currency we don't need to make fight others just because of money.