A bitcoin miner bought in Jan 2017 is already profitable.
Roque Solis who bought a Bitmain Antminer S9 on eBay for $2,400 has already mined 1 BTC and is profitable in 5 months.
So if you buy your own mining equipment it wont take you a couple of years to be profitable if you believe in cryptocurrencies.
Read more here http://www.coindesk.com/bitcoins-price-surge-is-making-hobby-mining-profitable-again/