isn't that how economic crises start or something.......?

Especially recent history has shown that stable coins should actually be written "stable" coins. The analogy to casino chips is also a bit weak because casinos (in many countries including the USA) are highly regulated by the government. An example of a USA law is that if a casino goes out-of-business, the cash assets that were set aside must be made available for people that were still holding that casino's chips so the person can turn them back into cash. No such rule exists for crypto "stable" coins.

When a "stable" coin goes under, you lose your money just like a non-"stable" coin. There are numerous examples from the last 5 years:

Most Expensive Stablecoin Crashes: The Biggest Collapses That Shook the Crypto Market