what should we do?

Well, I understand how you are feeling. I am a PhD student and I kinda feal the same way. I am feeling like I do not belong here and I am trying to find a way to feel better. In order to decide though what do you like to do, you must think a bit and ask your self a few questions. An undergraduate degree is a tool for your life, which if you have you can afterwards decide wether you want to use it or not (in any case it is better to have this tool in order to have the ability to use) So, my opinion is to try to finish what are you doing now and get your degree and after try to find something that you really like.

Hang in there. You are young, fresh and raw. You will discover your path when the time comes. Always follow your heart. Some people like you are probably unhappy because they are filled with uncertainty and maybe lost direction. I once felt like that when I was a fresh graduate, so I understand the feeling. After a few trial and errors, I began to discover what I am interested in and what I am good at, which is not necessarily the same thing. Starting off your career, a lot of people would think a good pay or high salary is the most important thing... but if you are more far-sighted, look out for jobs that give you more value, security and makes you more bankable in the long-run. It's too early to be tired... you are just starting a new chapter and be positive. You can try exercise to burn out all the pessimism if you want to go far. Still a long way to go.... all the best!!!