What do you do with the thunderbolt cable?

I'm sorry, but what is the point of the Thunderbolt cable? I have Apple just about everything, but I never use it. I would use it all the time to transfer the 128GB of data from my phone and iPad if there was A LIGHTNING TO THUNDERBOLT ADAPTER. Confused AF. The new Macbook Pro has 4 Thunderbolt ports. FOUR. I have NEVER successfully used the one I have. ONCE. I would like to know, people: "What do you use your Thunderbolt cables for?" (Besides external hard drives and displays).