Hardware wallet is safe as it it's not accessible to the hackers because of no connectivity to the internet. Sono one can steal your until he or she gets your hardware wallet.
But it is having some drawbacks as well as
Firstly as hardware wallet are actually electronic devices so they can be damaged by different factors.
Secondly if someone steals it then you are going to lose all of your assets and they would not be needing any key phrase to open it.
Both have advantages and disavantages between hardware and online wallet. But if we have big amount of money in crypto it's better to save it in hardware wallet because it's easier to save it from physical danger rather than hack from the hackers because big amount of wallet must be targeted by the hackers.
Seperating assets into multiple wallets is also highly recommended in crypto because if anything happen to one, we still have another backup at least.