If you believe this, what makes you believe that newer private keys are safe, if there is a way to hack private keys then no key is safe. With the technology available today, there's no way someone can hack your private key or seed phrase, except you expose it to them. Funds can remain inactive in wallets for very long, and it does not mean that the funds are lost, and whenever the funds are moved it does not mean it has been hacked, the owner of the funds can be the one who has decided to move it.