Would be safer for us if the hashrate increase was guaranteed, not the money spent for it. This way the asset is exponentially instable: should the earnings be more than necessary to keep up with difficulty, next they will be even higher, and so on indefinitely -the other way round, should they be insufficient, they will be even lower next time, and so on until not much is left. (but hey, yes, still quite better than normal bonds, I admit!
Now I see dividends going up... very good sign. But what about ASICs? The sudden need to upgrade does not go well with the commitment of investing only so much per period in increasing hashing power. Won't you be caught in a downtrend spiral low income-low investment if ASICS hit too soon?