The reason is simple . Most of the people who are in this field were not aware from such type of things but after the getting success in the increase in the price of the bitcoin , many people get attracted toward such things , because the main reason is that everything knows that price of the bitcoin will continuously in the future because of getting down in the supply rapidly .
Well when i was wity the work of bitcoin then at that time its price was about 200-250$ and i was not thinking about this to get up because the main reason was of the understanding ( that i didn't have at that time ) but when it continuously get rise then i told about this thing to many people in my society and they also started to make investment .
So this is the continuously increase in the price of the bitcoin that is making us greedy for the investment in bitcoin .