Bitcoin is the first successful project which achieved digital scarcity. Scarcity is one of the most important features in assigning value to a particular object. Bitcoin's scarcity is not only proven, but also completely transparent and trackable. Its scarcity does not rely on any centralized organization, it is completely based on mathematics and cryptography.
It may not have been apparent how ground-breaking or important digital scarcity was at the time. Most of the time when we think of money, we think about how we use it in our everyday lives. We buy coffees, we pay for an Uber. But underneath all that, there is a deeper meaning to money. Why do we value money? It really just boils down to scarcity, liquidity, demand.
Money has all 3. However, the scarcity factor of traditional money is flawed. It relies on centralized parties, for which money is not actually scarce. They can and do alter the supply at any time. It's a tradeoff we make because fiat is so liquid / demanded / transactable.
Bitcoin is less transactable than fiat money in most regards, but it makes up for it in the transparency of its scarcity. If you were going to lock your wealth up for 25 years, would you put it in USD or BTC? More and more people would say BTC. I can tell you how many BTC will exist in the year 2050. I would have no way to do the same for any fiat currency.
The main risk to BTC is some sort of technological breakthrough which greatly improves upon the concept of cryptocurrency. It's not that cryptocurrency will suddenly disappear or lose its value. Cryptocurrency is here to stay. We have witnessed the birth of a new asset class.