There are many reasons. For me, you can never make this fast transfers globally in the current banking system. But bitcoin is almost instant and it's extremely cheap. Sometimes it costs about couple of dollars. This is why people should use it.
Hackers and thieves cant steal your payment information from merchants if you are paying with bitcoin and use it for their advantage.
And unlike credit cards bitcoin is private, for example: your wife won't find out that you bought her present after seeing your bitcoin transaction.