Hey people of the internet

For years I have lived by the mantra of:
"if you want to love someone, love yourself first", many people have said it to me.
And its starting to sound more and more like bullshit to me. Narcissists love themselves too yet they don't seem to have the capability to love someone else that well.

I am not looking for a girlfriend to fix myself.

Have you heard this phrase before, and what do you think of it?