I will code for a few hours every day. But, if I have 100M USD, I will take most of the money and deploy it in all my hobby projects.
Some of the projects I like to get done are: App Reputation: Right now, all gamification is done by individual apps. For eg, Hashnode has reputation, StackOverflow has some reputation and so on. I want to centralise all reputation on a Blockchain so that it is not tampered with and is also made available in a central app.
Spend some money to irritate big enterprises like SAP, SalesForce by helping Open Source Software to compete with the big guys.
Bid on Indian government contracts and make the systems robust.
Fight for the cause of privacy by making people aware that governments are the biggest abusers of privacy of citizens.
Fight for minimum wages in India and make the minimum wages calculated on a hourly basis and make it INR 100 /hour.
100M$ may not be enough for all of this. I hope some of the initiatives will be money-making so I can use that money to work on my causes.