The crux of what makes it popular is decentralization which is a fantastic feature and I'd argue the single feature that it has that regular currencies can't ever have. However, everyone doesn't have a wallet and about 60% of all bitcoin is in the hands of only about 10,000 wallets. It's one of those things, if everyone had it then it would work great but because no one has it, it doesn't work at all. In order to get it you need someone you trust to trade you it, which means a centralized exchange, high fees, and slow transactions. However, if you only ever live in a bitcoin or other decentralized coin economy, meaning you never have to trade out of it into another currency, then it can work for you. Say Tesla accepts bitcoin, and everyonjhe pays in bitcoin, it still has to pay it's suppliers who don't accept bitcoin, this means it has to make a conversion to regular currency, adding an additional step, making things slower and less liquid. It's one of those things that just won't work, until it does.