People are attached to fiat because it (and more broadly, the state) gives them a false sense of certainty - through state schooling, propaganda and manipulation.
They think of their oppressor's fiat as a fixed measuring stick, and when you bring up inflation, they don't connect it to the stick's shrinking.
I saw a Reddit post recently where the OP, presumably based in the eurozone, was considering depositing EUR to an account and converting it to USD to earn a higher interest rate (5.1% on USD vs 4.1% on EUR). The commenters warned him it was "gambling" due to exchange rate fluctuations. As if holding the ever-devaluing euros wasn't gambling and a box of eggs was going to be obtainable for €2 in perpetuity, because somehow the "full faith and credit" of the EU means Christine Lagarde's indentured servitude tokens are going to be backed by a constant supply of chickens dropping eggs one after another, forever and ever.
The FIRE community, too, is fiercely against Bitcoin. However, people over in r/LETFs are warmer to it. Not because they've gone down the rabbit hole and understand its value proposition, not because they've studied monetary theory, or the tech, or believe in privacy and individual sovereignty, but because - as 'degens' - they're open to volatility and uncertainty. They may not be willing to hodl forever, they may see it more as a mid-term trade than the foundations of a new financial system, they may not have an understanding, but they do have balls.
Anyone who has studied human action knows that there is no absolute reference point for measuring value. Value is subjective, a good is exchanged for another good, and price is the exchange rate of the last trade. Money is just another good - and the economy may converge on one such good, causing it to become the most liquid good with the least decreasing marginal utility. But no one can guarantee its value, or, indeed, that it will continue to be used as money.
There is no certainty in human action and consequently there is no certainty in the market.
To go on a Bitcoin standard you have to embrace this fact, which may be scary to those who have fallen for the myth of certainty created by the fiat empire's brainwashing machine.
And that doesn't only mean the volatility on the NGU curve, but even the possibility it may go to zero.
But even if it does, at least you have accepted the truth; you may be broke, but your eyes are open.
Your alternative is to take the blue pill and wake up in your prison cell, with a bowl of rice, believing in the state's certainty fairy tale and being exploited by it until its empire falls and gets replaced by the next one.
What deters people from Bitcoin is their stupidity and ignorance, case closed.