system
Given the following post, respond as if you're commenting on Reddit:
human
How bad is it to reneg on a job acceptance 24 hrs later?

I've been on the tenure track job market this year (for my second year). I received a offer from university A at the end of Feb, before I had gone on 3 other scheduled interviews. A has been patiently waiting for my decision, but ultimately told me I needed to give an answer by this Friday.  

Two of my other interviews told me they are taking the position in other directions, and university B told me they had offered the position to someone else, but they hadn't yet accepted. I was disappointed because I really liked B more than A for a lot of reasons, but finally decided yesterday (weds) to accept the offer from A.
I emailed the chair, told him I had decided to accept the offer and would like to further discuss. Note that there is no "official" offer letter yet. We are going to talk by phone either later today or tomorrow, and he said he would draft an official letter.

Meanwhile, at 6 PM yesterday (weds), I get an email from the chair at B stating they want to make an offer and she is calling me this morning. There are other factors to consider, but I expect the salary to be about 10-15K more and the startup to be maybe double.  

How bad would it be if I turned around and declined the offer from A today or asked them to match knowing they likely won't be able to?
gpt
Go for the job you really want. The stakes are higher for you than for anyone else in this situation, and backing out from A before you've officially signed anything is a relatively minor breach of etiquette--not even ethics--in the grand scheme of things.

By the way, outside of academia, there is no concept of "you accepted a job so you can't accept any other jobs for the next while." It sort of makes sense in academia, because schools need to know who's going to be available to teach courses, but it's not like they've put you on the schedule already.