I personally don't think it's a pyramid scheme haha. They say the estimated last bitcoin to be mined will be in year 2140. How much longer we can make money depends on where the price of bitcoin goes and how much you have to risk in a miner. You have to stay ahead of the game when it comes to miners to "make money". Some would say to just invest in Bitcoin directly and others will invest in mining hardware, really comes down to personal choice. Just my 2 cents