Do you owe them something? If you are happier in your new job, isnt that the first priority? Also, more educated people arent necessarily smarter than you. And even if they are, the main thing is are those people worthy of your trust? I would rather trust an idiot that genuinely wishes me well than extremely smart person that has been mean to me. Have they treated you well and given you good advice before? Have they made your work experience better?

And finally, compare the payment your get now and you got on your old job. Is the difference worth the increased stress and bad sleep?