Bitcoin has a production cost! You need to invest in an expensive mining right to be able to mine it. Also there's a recurring cost of electricity and colling. So when an asset has a production cost, it will have value. Because a miner is not going to give away Bitcoins for free.
It's not really a production cost. The "cost" isn't fixed, it varies with difficulty, and difficulty reacts mostly to three things: electricity costs, technical progress (Moore's Law), but mostly the Bitcoin price itself. Thus there is some circular logic in the argument that Bitcoin has value because it has a production cost. Because the production cost does also depend on price ...
In addition, NFTs have also a (small) production cost if we follow that theory: transaction fees. Of course the idea of NFT investors is that NFTs should yield a profit. But for the Bitcoin miners, actually that's the same; they often hold some
BTC in reserve and speculate with a higher price, and above all those who mined early, before the emergence of the big "mining industry" (let's say pre-2015) in many cases held all of them for later. So according to this price theory, Bitcoin and NFTs aren't that different.
But I actually agree that Bitcoin has a much clearer intrinsic value than NFTs.
In my opinion, Bitcoin's value is described relatively well by the "social network theory", i.e. the more people use it as a payment network, the more value it accrues. Bitcoin encompasses also the blockchain, i.e. the infrastructure to transact. NFTs do not really support this infrastructure, and their social network is much more limited.