Binance is a good exchange indeed, a few times ago when a bad thing happen they replace all the user fund and also they promise that the incident is the last because they will tighten their security so that hackers can't get into their security system. However, it does not guarantee that their security system is safe by hackers, hackers must have many ways to hack them back. So, I don't think a good idea for someone who have an intention to hold their bitcoin a long term investment in the exchange. As other people above me said you must choose cold wallet to store your bitcoin, the security is depend on your hand.