Share price is priced at Mr. market's expectation which usually...

Share price is priced at Mr. market's expectation which usually leads to overreact.

Share price usually shot to the moon due to optimistic expectation at the early stage;
Then price is smashed to where it started due to not meet the initial expectation, lead to be disappointed and over pessimistic, causing 'end of world' reactions.

BUT, that is how a great opportunity is emerging.
However, it's important to understand the business and its financials to avoid picking up a complete "dead cat".