Unable to log in to my account

[Tiberius]

...and that brute force attack would take a tremendous amount of time and resources for each user.

This.

LastPass by default takes your master password and hashes it using PBKDF2 5,000 times. That slows down the key generation process enough to effectively make attempting a brute-force a waste of time.

Ironically the fact that LastPass got hacked actually made me trust their security more, because as far as I am aware, the hackers never actually got into any of the password vaults, meaning their encryption protocols were top notch. Sure, it's a shame their infrastructure was breached, but the important thing was the data was still secured.

[Jackalope]

I did a little back of the envelope math, and with some generous assumptions (such as being able to test 10^6 passwords per second) that breaking my password by brute force - which would be the only way it could be done - if you knew the passphrase length...

Heat death of the universe would come before you'd crack my vault.

[Minimalist]

My LastPass password is 30+ characters long (it's basically a nonsense sentence)

I'm 66 years old.  I'm lucky I can remember your name let alone 30+ characters.