People who buy bitcoin are people who are still convinced and believe that bitcoin is a good asset in the future. They may not be able to predict how bitcoin will be, but they are sure and dare to take risks to still buy bitcoin.
While no one can tell for sure the time when Bitcoin (BTC) and crypto in general will rebound, there are a few pointers that indicate a possible ending to this bear-run. The first one may sound counterintuitive, but its a good measure of possible market direction, and thats the sentiment of the average investor.