At the moment, it is not a viable business opportunity, unless you have millions of dollars to start big. However, as the most advanced technologies are being used to manufacture the ASIC miners, the jumps in hashing power (for a given power consumption) is starting to slow down.

For example, in 2013-2014, for the same amount of energy spent, you can have 5-10x more hashing power if you wait a little longer, because more efficient miners are being made. That was the time when the ASIC manufacturer will "delay" the delivery of their products as they can use them to generate bitcoin for themselves.