Bitcoin can exist without trading, it has done so for years.
Bitcoin can't exist without mining, the moment that stops you can't transfer value anymore, it's done.
And no, trading is not something that Bitcoin needs, moreover, it's trading that affected its adoption as a currency.,
We can elaborate on this: the Btc blockchain will still exist even if no transactions are made, we'll have a series of empty blocks, similar to Ada's situation before. However, if miners no longer operate to maintain the network, the blockchain won't be able to exist, and that native token, along with many other tokens in its ecosystem, will lose all of its value, possibly temporarily or permanently.
We can also look at the issue more openly: the Sol blockchain has experienced many outages, but SOL still has a high price and a much larger marketcap than many other native tokens in the crypto market. Ultimately, investor confidence will determine the value of an asset in the market.