All depends on ones goals and plan. Always more risk when buying potentially disruptive biologic stocks. That said, there are much bigger multiples of profit that could be realized than buying an established market leader. My plan has concluded that a $40+ upside is worth some risk. Therefore, the last 10+ years has been mitigating risk focused as well as position growing. Personally, no way I would want to be without stock in AVXL at this point in its development.
Just me. Wish everyone blue sky and green returns.