What it means "to be a data scientist?" It means that you call yourself a data scientist, and that someone pays you to do things that either you, they, or both of you, agree are "data scientist" types of things. If you're not getting paid, then I think it makes you an "amateur data scientist", "data scientist in training", and "intern data scientist" or my favorite, an "indentured data scientist." There may be other amazing terms to describe this phenomenon (unpaid data scientist) but I believe I am missing them.
I could be a "data scientist", "programmer", "technical manager", "software engineer", "software architect", "pimp" or "software gangster." I prefer to call myself a "contractor" or sometimes "consultant" though. The last two tend to have the type of tax benefits I like, and don't really result in a customer specifying the time, place, and manner of my work to the same degree as if I used the term "employee."
The only person that I've met that I wouldn't feel like punching them in the face for them calling themselves a "data scientist" had a masters degree in statistics, was super good with relational databases, and all right at programming (but not awesome.) I do live in New Mexico, and we aren't exactly trendy, so I can imagine a lot of people that might be legitimate (not amateur) data scientists that live here call themselves database administrators, or programmers, since they aren't concerned with what Dice says they should be making as a "data scientist."
To me, this distinction has no use. That may be because I don't want to be a "data scientist" or spend time with them, despite working on analyzing large data sets and doing "data science" for paying customers.