The reason might be they already got enough profit during the last boom of crypto market, they are tired, they don't have a patience, they cannot wait for longer to get profit, or maybe the got scam, so they don't wanna try it again then they are leave. People who invested earlier in Bitcoin earned a million dollars and they can settle now a new business. For this reason, the crypto money has attracted the attention of the whole world and invested but the price went down.