I just want to know how those people behind bitcoin secure the money they will invest because as far as I know there are lots of hackers all over the world.
If you are going on an investment, the first step you will do is to review the project you are joining. Check the website, whitepaper and the road map of the project. That is if you are joining in an ICO, most people do that. If you are worried about hackers, then you pray that you cannot get hacked, your wallet cannot get hacked even thr project.