Retire. $750K is $30K in passive income for the rest of your life (assuming you already have a residence).

Welcome to complete financial freedom to do whatever you want in life [0]. You don't necessarily need any more money to be happy [1], and the point of getting filthy rich is to attain freedom of time [2], which you can get if you just live cheaper [1 again. Seriously, read this].

So really, this question should be: what would you do with your life if you could do anything you wanted? That, I'm afraid, is a much more subjective and philosophical question that the margins of this comment are too small to contain a satisfactory answer to.

0. Unless you have substantial current debts. If so, pay those off first.

1. http://www.mrmoneymustache.com/2013/02/22/getting-rich-from-...

2. http://www.amazon.com/How-Get-Rich-Greatest-Entrepreneurs/dp...

That probably depends on what one wants to do, but some people do suggest that being ruthless is the ultimate way. Example: http://www.amazon.com/How-Get-Rich-Greatest-Entrepreneurs/dp...

Point is, if one is not willing to do whatever it takes, he probably doesn't really want to do the said thing, but rather tries to live up to social expectations.

How to Get Rich: One of the World's Greatest Entrepreneurs Shares His Secrets - Felix Dennis. The most life-changing book that I read this year. http://www.amazon.com/How-Get-Rich-Greatest-Entrepreneurs/dp...

Best book on the topic: http://www.amazon.com/How-Get-Rich-Greatest-Entrepreneurs/dp...

http://en.wikipedia.org/wiki/Felix_Dennis