They are attracted to the sweet smell and taste, but in fact if they drink it it kills them.
Yup and its a slow, painfull horrendous death so please make sure to keep it locked away from where small animals could get to it.
Also to OP stop being so lazy, take it to the vets and get it scanned ffs.
Someone could be out there spending a lot of time and money trying to locate their cat, never know they may even cough up a reward (I know I would for my cats).
Never know could belong to some massive meat head dude and one day he'll walk past yer house and see HIS cat in YOUR house! Knock on the door and not be the nicest of people.
Not to mention the cat may have medical conditions or need medication regularly, you keeping it at home just because you feel like it could harm the cat.
It may be chipped, it may not, do the decent thing and take it to the Vet.
As for your comment about a cat being let out early morning not being a responsible owner?
I have 2 cats, both chipped, both insured, both with safety/quick release collars. They let out early morning (Before we need to goto work) and late at night, before we go to bed. do you think its fairer having the cats cooped up all day in the house?