#港股币股热潮 What is a stablecoin? I feel really confused. Recently, there's been an overwhelming amount of information, as if another opportunity to make a fortune is coming. Those who missed out on Bitcoin have a chance this time, right?

I have never truly understood Bitcoin until now, when I have slowly started to grasp it a bit. Why has Bitcoin increased so much? I think there are two underlying reasons: one is that the supply is limited; the total amount of Bitcoin is capped, making it hard to mine more. The second reason is that Bitcoin has its practical uses, especially for some illegal transactions. Due to the high demand for illegal transactions and the limited supply of Bitcoin, the price of Bitcoin must rise. The increase in Bitcoin's price causes its total value to expand, thereby meeting the demand for illegal transactions and the subsequent need for wealth preservation.
So, do stablecoins have these two conditions? First, how is the issuance authority and issuance volume of stablecoins determined? Is it highly restricted or can the supply be increased at any time as needed? I haven't researched information about stablecoins, but from common sense, since it is determined by official authorities rather than being algorithmically locked like Bitcoin, it is highly likely that they can be issued as needed.
How to use stablecoins? Are there any specific scenarios where stablecoins must be used for settlement? Currently, whether it's for daily transactions or international trade and investment, using fiat currency is very convenient, unless it's for illegal transactions.
So I don't quite understand for now, what's so exciting about the official increase in currency issuance? (Forward)