I think The amount of unused Bitcoin which is now at its highest ever at 70%, shows that people who own it don't want to sell, even when the price goes up. This Bitcoin hasn't been used for over a year.
This is not entirely correct.
Let me put it this way, imagine you earn $2 (two 1 dollar bills) but only spend $1 and keep the other. That doesn't mean you didn't spend your money. That means you only spent what you wanted to spend.
In a lot of cases in bitcoin, this is what's happening. For example I own some coins I have not touched ever since 2014, didn't even claim the shitcoin airdrops. That doesn't mean I have never spent or sold my bitcoins. I have other coins too, for example I got some a couple of days ago and if I want to spend/sell some I would spend/sell those not the ones from 2014.
Since Bitcoin reached its highest value in 2021, people who plan to keep it for a long time have shown they really believe in it, despite problems in the market and with the economy.
The same. People who have bought bitcoin, do believe in its long term potential but when there is economic hardship they don't have to dump all their stash. They can sell some to cover their costs and keep the rest.
In any case, people are always going to keep more bitcoin than they spend/sell because in the long run the price is guaranteed to rise, this is not just because of bitcoin's potential but also because "price" is measured in fiat terms and fiat is super inflationary thanks to constant printing of it.