We only offer accounts on the site via Steam logins, so for someone to gain access to your 'account' on the site, they would need full access to your Steam account in the first place.
Steam offer 'Steam Guard' as an extra layer of security, requiring you to enter a unique code whenever you log in to Steam. If you haven't already, we recommend you set this up on your account. More information about this can be found here.
We do also offer additional security on your account in the form of 2FA codes, similar to Steam Guard. For more information on this, take a look at our '2FA (2 factor authentication)' section.