many cases of bitcoin wallets being hacked, and it is not an open secret. now the most important thing is how we secure our own assets by storing our wallet passwords safely to avoid being hacked. because any kind of security is easy to hack by professional hackers
One important thing is to not publicly talk a lot about your portfolio because that may make you a target for social engineering. Many people brag about their portfolio in public and I think that is not very smart. Rather keep quiet and enjoy.
Other than that there is a variety of things you can do. I wouldn't recommend holding too much in a single wallet for example. Split it up such that you can bear the loss of a single wallet. Use a hardware wallet and so on and so forth.