They spend millions on building and maintenance of these rides. They are very safe because they are constantly monitored and well maintained i personally never been to six flags but i have been on some crazy roller coasters and they have advanced computers and systems monitoring every single piece of track on that roller coaster. well have fun if you decide to go. And keep in mind that millions of people get on roller coasters each day and the worst that happens to them is probably nausea or stomach ache :P
well, think of it this way. six flags has been around for a long time. it hasnt been shut down. if the rides were that unsafe and really had that much of a chance of killing people then they wouldnt be open. of course, evantually someones bound to get hurt, or even worse, but that just happens. its a theme park, you cant expect someone along the line not to get hurt.