I ran a standard raspian ssh server on my home network for several years, default user was removed and my own user was in it's place, root was configured as standard on a raspbian, my account had a complex but fairly short password, no specific keys set.
I saw constant attacks but to my knowledge, it was never breached.
I removed it when I realized that my ISP might take a dim view of running a server on their home client net that they didn't know about, especially since it showed up on Shodan...
Don't do what I did, secure your systems properly!
But it was kinda cool to be able to SSH from Thailand back home to Sweden and browse my NAS, it was super slow, but damn cool...