#62
Set up a joint venture with a friend selling tap water.  Hire a bottle designer and a team of marketeers, gathering funds via share distributions.  Illegally set up your business outside of schools, festivals, company buildings, city street malls and so on.  Pay people to graffiti your logo everywhere (aka free advertising).  Pay strippers to advertise your product as well (they can be quite convincing).  Then store up LOTS and LOTS of tap water, which reduces the available supply of water to the public and either drives up the cost of water, or causes the government to put restrictions on water (if not, lobby).  Now with your monopolistic position in the tap water market, start earning big $$$.  With that, expand the business internationally to penetrate more markets.  Whilst doing this, buy out all the ports in the world and invest all this money into desalination plants.  Make sure you make the entire sea (aka 70% of earth) under your control.
After you've done all that, sell the business, dump the money on the street somewhere, and keep $10 for yourself.