10m wouldn't be the house, you live in a normal 300k house and pay no rent, the 40k covers all your day to day expenses, and you don't need to work. In reality you can probably levarage your security and contacts to get yourself a nice cosy consulting job.

Of course you could decide "I have 10m, I'm going to spend it". Thats your choice.

With 10% growth and 2-3 kids you can pass that on indefinitely to all your children even if all you do is a typical middle class office job.