can explain the reason behind those huge pump and dumped of BTC?
When there are possibilities for happening of pumping, then you need to be prepared to face dumping also. No market can move in one direction all the times but basically bitcoin is designed to have huge value over the time due to its limited supply hence we can expect bumping to be happening over the years but in between years we can expect dumping also to be happening which may happen up to 70% of each ATH (as that past events).
Crypto market is untrustable as any person having a status/huge bank balance can easily manipulate the market as Elon Musk did.
No, you are wrong. If bitcoin is not trustable just because of with the reason of easy manipulation, then how you got chances to see bitcoin is growing from $400/$700 to current levels of 30k+ ? People who are investing into bitcoin must need to understand its high volatile nature. If you're able to hold it for years then you can easily eliminate the problem of high volatile nature of bitcoin.