It's built into the fundamentals of Bitcoin that once it attains a value, that value can only go up.
You'll need to define what you mean by "value" here, because Bitcoin has attained a value in the past that is much higher than its current value.
The fundamentals regard the technical aspects of the coin, not the human element, which is responsible for the price action.
Of course there are and always will be external elements. Market manipulation, hysteria and mania, technical glitches, trading bots etc. But the law of mathematics backing Bitcoin is that,
when something has a value and is deflationary, that value cannot but go up. So as long as Bitcoin is used, it will have a value and that value, fundamentally speaking, can only increase in time. As like the value of fiat money that is inflationary, fundamentally speaking, can only decrease in time
No, this is wrong on so many levels. There is *nothing* about a deflationary currency that says anything about what its value will be or how it is determined. Instead, people ascribe value to things.
When you talk about the value of something, you need to ask the question, "To whom is it valuable?" Bitcoins are traded in an auction-style market. Bitcoins are only valuable to its users and indirectly to non-users who are impacted financially by BTC users, or more simply put, bitcoins are valuable to those who believe they are valuable. All it takes is for people to believe they aren't valuable or to stop buying and using them altogether for them to become worthless.
You can have inflation in a deflationary-currency market (like we have right now with BTC). You can also have deflation in an inflated fiat currency market. In neither scenario is there any information that tells us how to calculate or predict the value of a currency.
It's axiomatic that if you take away the people that ascribe value to BTC then BTC would have no value. Value comes from those who subjectively ascribe it.