I figured out that i can also can dump my privkey while disconnected to the internet but does anybody does that?
First of all, you have to keep in mind that if the malware is there, it can send out info at a later point too.
Second, I guess that you can always unplug the network cable, stop the WiFi or so for disconnecting. Is that an issue?!
Also those onlne paperwalletgenerators are a risk, what do ypu people think about that?
The proper paper wallet generators also offer a link (gihub usually) where you can find, zipped, the whole website.
This allows you download, unpack and run that page locally, without internet, preferably on a safe enough operating system, and print that paper wallet(s) on your local printer.
If you are careful enough, this is one of the safest (and cheapest) methods for building yourself a wallet.