From what you've said about bitcoin, there's really a lot of reason why bitcoin is better than cash. Bitcoin can give people an extra salary, it's good for investment especially in a long term, and many more benefits to us. But as of today, a large portion of the world were still using their real money - their currency, to buy everyday needs, use as payment in many transactions they do, and more activities. Maybe, we can really say that bitcoin is better than cash if it's already acceptable as payment mode whether online or offline in each part of the world.