Complex answers for a simple question

A few days back, I came across a fascinating set of answers to a question on an online Q&A forum. The questioner had a happy problem-he had inherited $15 million and wanted to know how he should invest it. He said that he didn't need the money for about 15 years. His own idea was that he should put the money in three to four index funds from Vanguard, which is a US mutual fund company that is known for ultra-low-cost index funds, and just 'sit on it' for 15 years. However, he wanted to know what the online community thought he s