Why do you care? is a question Rey asks herself often. She isn't supposed to, because caring is inconvenient, makes you emotional when you latch yourself onto cannon fodder. Over time, though, she ended up being rewired differently and, well...

Here we are.

"It's less about who and more about what. That ship is what brought us here, for no real rhyme or reason as far as we can tell."

Yeah, she's not going to answer the caring part.