Just disconnect from internet and no one can hack you unless you install games full of viruses.
The ideal behind cyber security is that you can operate safely in a hostile environment.
Just use local network.
You can still hack it
Also, paying a hacker who hacked you is very dumb. Like, it just encourages even more hacking and rewards literal villains.
The government has considered making it illegal to disincentivize paying ransomware groups but then companies will still pay. I want my data safe even if it means paying a ransomware group. Maybe if you don't want to lose millions of dollars you operate a bit more securely, but don't punish me, your customer by not paying the group.
There is also another problem with airhapped networks like you are talking about.
The CIA triangle has 3 things you try to do as a security professional.
1. Keep data confidential
2. Integrity- make it so you can trust the data. It hasn't been altered
3. Availability
You violate the A part of the CIA triad by making the information unavailable.
It also violates the principle of being able to safely operate in a hostile environment.