So first I would use 5 trilling dollars to solve death, cancer, and other things in that category.
Then I would take another 5 trillion dollars and make extremely advanced AI robots.
10 trillion for spaceships that can go at least 1% the speed of light.
Using the spaceships and robots, I would fly to Mars and setup a huge place (basically like building your own continent except on Mars) for my family, thousands of people that are willing to pay high rent and follow my strict rules, and I to live on. I would become dictator of Mars.
I would give a few thousand robots a budget of about a billion each for them to make other robots and setup hundreds of businesses that will each be better than businesses like Apple, Walmart, Microsoft, McDonald's, and some other really good businesses that I can't name off my head.
About 75 trillion left still not including my business profits.
I guess I would colonize the galaxy with 50 trillion by using the spaceships than I have talked about and thousands of automatic robot-spaceships that harvest planets and stars.
25 trillion left over. I'm just gonna keep this in my back pocket just in case I need it someday.