There is basically no company that wouldn't rescind an offer if it made the difference between 1x profits and 1.5x profits.
Why wouldn't I behave exactly the same way if another company offers me 1.5x the salary?
Why wouldn't I behave exactly the same way if another company offers me 1.5x the salary?
edit: Since I can't delete my comment now, I just want to apologize that I read your message too quickly and missed the 50% salary difference part. Come on, there's ethical and then there is crazy, of course you leave and take the other offer if it's 50%, that's common sense and any hiring manager should understand it. But that's not really commonplace and you can handle it in a professionally ethical way.
Don't let profit driven corporations brand themselves as "family", or any other concept which deserves moral consideration.
I'm joining a business, not the Knights Templar.