Objects can get flung out of solar systems when they pass close to large objects. Similar to how spacecraft get gravity assists.

A very rough calculation would suggested that the cylinder that goes from our solar system to Proxima Centauri contains 5000 similarly sized objects moving at the same speed:

1 object crossing the solar system plane every 5 years at 60km/s

+

Proxima Centauri is approximately 5 light years away

=>

there are `speed of light / 60km/s` objects in the cylinder.

> But seriously, why would interstellar objects come towards our solar system?

Why wouldn't they?

Because to go through plane like that they need to match our solar system speed relative to galaxy.

Universe is big and full of random small rocks floating around everywhere.

Why should I believe some object was _intentionally_ thrown here? Maybe it is just one of those random rocks.

> Floating around everywhere.

Sorry to be pedantic. But space is really, really, really... empty. That's why the best name for it is, space.

You can go outside at night and see big rocks floating. If space is so empty, how is it possible that you can see them with your own eyes?

We live in a patch of space that's not that empty. Maybe that interstellar rock floated from other patch of space that's not that empty all the way over here, all on its own.

Most rocks we see in our patch of space, as far as we can possibly know, were not intentionally launched.

Because space is big. Really really big.

The ocean is big compared to a fish, but I can still find fish in it quite easily.

There's nothing statistically weird about these interstellar objects.