If we are talking about this say two or three years ago, I can say that yes Bitcoin mining is costly but it is a great idea and is very profitable. But now, as we speak, I don't think so, before mining is costly but it has great returns now, it still has good returns but the cost has sky rocketed that the good returns may not be good enough in the long run, most of the necessities on mining like the mining rig, equipment, electricity and all the stuff cost way way higher now due to the fact that it is being used for Bitcoin, so the profit is not as big as before since the investment capital alone is already high.