It's the classic "It's popular now, I must join in the fun!" Everything that involves money and trends, it is always the laggards that suffer the biggest losses because the cheese stands alone.

Ponzi schemes and all markets function the same way because it's human nature to follow the herd.

What you should have done is wait for the market to crash before investing (not buy during December 2017!). Today might be the best time to invest. A year from now or two might be the best time to sell. You just have to wait for another parabolic price trend.