How can I buy pi? Only on the listed exchanges or can I trade from the Binance wallet?

Reasons of Pi coin Crash..

From $97 To $1.09

It has happened with other crypto projects in the past as well, despite all the hype associated with them.

frist reason it was free .Early miners profit taking
Pi Coin’s oldest friend can turn its latest foe. Early adopters have patiently spent a lot of time to amass a lot of PI coins. These miners have waited for over 5 years, and this will be their very first chance to get an exit. 

Lack of Real-World Utility

Let’s face it, the Pi network lacks real-world utility. Beyond the P2P transactions, no other use case has been properly explored. Yes, there are dapps being built on the apps, but only the number is low, and most users are unaware of them.

If the Pi Network ecosystem doesn’t develop a robust network of decentralized applications (dApps) and partnerships that drive demand for the Pi coin, a crash is inevitable which you are seeing now ...