[jeroenhd]

If you use a good password (meaning a unique, randomly generated one), or disable password login and use private keys only, your chances of getting hacked by any of these are abysmally small.

There are reasons to lock down your SSH port (fear of exploitation of the SSH software, like in the xz backdoor scenario) but I generally wouldn't worry too much about all the failed login attempts in your SSH log, as long as you're using secure enough login credentials.