If you are then read on … if you are not, then just ignore the rest of this post.
For a start you listed first the 3 reasons for not going for the job – then followed up with only one reason for going for it which was : “I want to apply for it because I know the environment and i will be more happier there.”
Now do you know this to be true? If you last worked there several years ago it will not be the same environment and things will have moved on without you – so you will be coming into a different environment perhaps thinking nothing has changed. You can of course do some research to see if things have changed for the better or for the worse and then make a decision.
If you then make a decision to go for it – I would then think “what is the worst case scenario?” Which I guess will be being turned down for the job. Could you live with that? Most importantly, for you is, would it lead to gambling thoughts …
Do the research – decide with your head not your heart and live with the outcome whatever it is. I wish you well.