its late to invest ,imo.
Because the BTC exchange rate is fixed and will never change, so he'll never recoup any money he invests in hardware today 
If you expect the exchange rate to increase, then it is more profitable to use the money that you would have spent on hardware to instead purchase BTC. If you already have hardware, then if the cost of electricity per BTC is less than the exchange rate, then it *may* be more profitable to mine. If you have excess hardware then it may be more profitable to sell the hardware to purchase BTC.