i will keep 50 bitcoin in a trezor hardware, 2 bitcoin in each of exchanges let say i used 5-7 exchanges for doing trading), the rest maybe i will save it in blockchain and i am not using the amount in blockchain in any purpose except i am on emergency situation. its the best way that we can do if we can save our bitcoin in many wallets but we need to managed on every wallet.
I hope you realize that hardware wallets can be hacked into. I read somewhere that they were able to retrieve private keys from a trezor by monitoring its power output with an oscilloscope... Not even anything near a difficult software hack, just a little tinkering and probing... They've upgraded it since then, but there are probably other ways of bruteforcing it.
I politely suggest you do more research. In 2015 a hardware/software engineer managed to extract the seed from a trezor using specialist equipment. However this security issue was promptly fixed with a firmware update and in addition to having the required knowledge and equipment a thief would also have to have the actual trezor and the correct pin , pls remember the time delay with every wrong entry. I.e. 30 + entries = years. The engineer who did this now works for trezor. Hacking is nearly impossible due to the fact that the best hardware wallets never actually connect to the internet directly.