I have actually never heard the word "travelholic" but if you wanted to create the word, it would be "travelaholic". Americans put "aholic" at the end of things sometimes to emphasize doing something to an extreme. "Traveler" is correct but does not really convey that someone travels a LOT. In English, someone who loves to travel is sometimes said to have "wanderlust" (wander=explore and lust=passion). Sometimes this is used for someone who dreams of traveling a lot even if they do not actually travel. For example: "Are you leaving again? You really have wanderlust!" If they travel around the world, they would be called a "globetrotter". If they travel so much that they don't have a true home, they would be called a "nomad" or they would be living a "nomadic" life (not staying in one place for too long).