Copying text can be done.
The ease of it depends on what the reader is using.
You can highlight passages on your kindle and then find the highlights back through your Amazon account under Your Kindle.
By using the kindle app for pc, whole books can be copied, but it takes quite a bit of effort.
Pirates usually only go for free content tho, they're not the paying type.
So if you don't set your book free, you probably have nothing to worry about, and even if you do (for promotional reasons) there's only a small chance they'll actually pirate you.