It's fairly unlikely in a civilised surrounding, but civilisation is rarer than you think.

As a straight white male, your potential downside from getting into a chat with someone at a party does not include serious bodily harm. Most people are nice to you by default.

Another example: an outgoing, alone woman might be perceived as easy or sleazy by some Neanderthal-like person she talks to, and could end up with a lot of unwanted attention from saying hi to the wrong people. Again, unlikely, depends on the surroundings/crowd, but still.

As a white straight guy, going to a totally random party alone is a much safer proposition.