Barry Diller's People Inc. is offering to buy the rest of MGM Resorts after acquiring a 26.1% stake in the Las Vegas casino and resort operator, valuing the business at more than $18 billion.  People Inc., formerly known as IAC and owner of publications including People magazine, began investing in MGM Resorts about six years ago, according to a company  statement  on Monday. The company is offering $48.30 per share in cash, or a 10.6% premium to MGM Resorts' price on Friday.  In a statement,