I do not fully understand the cryptocurrency domain but have always wanted to gain a better understanding of it so am hoping for some insight. I thought that one advantage of Bitcoin was that it cannot lose value?
It's decentralized nature
That it can be anonymous, and by default is more "anonymous" than other online payments. For example, you would only know my wallet address, while something like Paypal/Venmo would give you my full name and email and maybe even physical address. You could probably do some digging with that wallet address and find my real info, but it's certainly tougher than having it emailed to you.
That payments work like a "push" rather than "pull". A store/vendor gives you an address and you send them BTC, they then wait for the funds to land in their wallet. But with a credit card, I give the store my credentials and trust them to only take as much as promised and not charge me multiple times.
Also, it's definitely used more for investing/hoarding at the moment than it is as an actual currency, though more and more companies and payment processors are beginning to accept bitcoin as payment.
Maybe what you're thinking of is the fact that it's deflationary unlike fiat: there's a finite number of coins that will ever be created. In other words, if you own exactly one dollar, over time, the percentage of total dollars you own will decrease, whereas with bitcoin, one bitcoin represents a constant fraction of the total bitcoin that will be created. This says nothing about how many gallons of milk one dollar or one bitcoin will buy you though.
Value is another question altogether.