For me, the biggest reason not to invest in Bitcoin is that there is no certainty of the future and hence I am not investing my entire wealth in it. However, I am impressed with the core philosophy of Bitcoin and I am optimistic about it and hence I am investing my some part of the wealth which I can afford to lose because I want to participate in the process of global transformation which takes place once in the century and that side is always bigger than possibility of losing my funds. I can earn money later but this opportunity won't arise again in my entire life so I am okay with 100% loss of capital considering the other side.