In my opinion, speculating is risker than mining as the fluctuation range is large and very often the price of coins is affected by the market, policies, news and other factors.

It is more suitable for mining when the market is sluggish or in the downtrend as the mining machine price reduce, difficulty decreases, miners can mine a stable amount of coins over a long period of time, when a bull market arrives, miners can sell the coins they dig up in a bear market for a huge profit

In Short: "Bear market mining, Bull market speculation"