It sounds simple, but it is difficult to perform. The volatility is really unusual.
But the history of bitcoin has shown that, in general, if you hold you win.

I think the volatility status of the bitcoin is excellent at the moment. If you look at the Ethereum, bitcoin is much more stable.
Don't compare ethereum and bitcoins because it is way more different, bitcoins is controlled by the majority volume of users but etherium is I don't know right now, I think it is controlled by the whales and anytime if the whales feel bored they play with the price. I would never put my investment in ETH for long term as it is just all about the game now.