Bitcoin has all the advantages of digital cash and allows one to be in control of their money. Although involves taking security precautions, it's what makes it such a good currency for the future.
That's true and it is the only currency whose value keeps on increasing, and if it can be the best investment for future too and that makes bitcoin unique from other currencies.
Investment opportunity from a payment system is an extra benefit we can enjoy only with bitcoin payment system. This opportunity for investors will bring more people into bitcoin system to make it the best future currency without any doubt.