maybe because bitcoin is a workplace that is very easy to get money and income to meet economic and other needs.
Bitcoins is easy to get but not easy to multiply because the market price is depending on supply and demand so you should always study the situation before investing or selling your coins.
Bitcoin can be multiplied if you know how to trade. For example: In the first half of August the bitcoin price has increased by 50% and is now back to around $ 6k. If you know for sure you will receive a 50% increase in the amount of bitcoin