Re: They all want to marry doctors and dentists and millionaires…
Just guessing here. She probably did it for the sake of her nephews and nieces. Better their khala be their stepmom than some stranger. Maybe, she knew her former BIL, now husband, to be a good person.
Both spouses having Ph.D does not guarantee mental compatibility I think. The only way to judge mental compatibility is by talking, spending time with someone.