How secure are accounts that have yubikeys really?

Idk what the point of this post is really. I have yubikeys on all major accts FIDO2 where possible and yubico authenticator app for all others that dont allow FIDO/U2F. I have removed cell phone from every acct i am able to. Yet i still get paranoid about someone hacking my accts or stealing my identity or something. I am pretty “low risk” online (e.g., dont download anything, dont visit sketchy sites, dont open emails unless im SURE, etc). Basically i try to just use computer / internet for essentials like bills, etc. I have no social medias. But i worry that idk someone will try to recover my email address and will actually get in somehow (i am very aware of session stealers and even though idk if i do anything to get one anyways, i always logout and clear cookies before turning computer off)….does anyone else understand me on this? Or am i just blowing this way overboard? Do you guys feel pretty reasoably safe with yubikeys protecting your accts? I guess my lack of faith comes not in yubikeys, but in these services that i am (sometimes) forced to use..