Will i get my butt kicked in a street fight if i do karate?

It depends on what kind of dojo you train in and its instructor(s), and how much effort and time you put into training. If you train in a dojo with a major emphasis on competition and your goal is tournament trophies, then you will be in trouble in a real world self defense scenario. So, if self defense is your goal and you're interested in karate, look for a legit traditional karate dojo with a good instructor.