You don't even need to do this - if you need a trillion dollars then just get in your time machine once it is built, head back 25 before today and invest $1 in

You don't even need to do this - if you need a trillion dollars then just get in your time machine once it is built, head back 25 before today and invest $1 in all the hot stocks and winning lotto number so that by today you have the trillion you need to build the time machine. Simple.