~snipped~
You can lose your bitcoin if a hacker get access to your wallet private key and move your bitcoin to their wallets.
Your response, going by that comment, wasn't what OP was asking and to which I responded. Let me refresh your mind on what OP asked again... 👇
Unlike fiat which the amount in your bank account remains what it is, bitcoin in your wallet will constantly fluctuate, meaning that there is chances that you can gain or lose your bitcoin.
OP wasn't referring to losing one's Bitcoin to hackers or anything of that nature. Rather, what they were asking was if there was any situation that would make one's Bitcoin hedl to decrease in its unit. Let's say 0.005 BTC reduces to 0.004 and continues that way until it gets to zero.