yet people are complaining that it has been a bad investment
I think that is because in the long run, people tends to be used in the fast changing price of Bitcoin and that is not dumping but they are used to pumping. Since the price are changing fast, they always think that it will always be a pump and they are scared of the dump. They are complaining since they are scared of what may happen in their investment.
Maybe yess because in bitcoin you can take advantage of fast changing in value to earn profit. If you invest in bitcoin that much and have enough patience as well you can earn bigger than usual because if you are wise you will not rush to sell your bitcoin. Investing in bitcoin is really great because you can also earn double or triple.