It only makes sense if the number of miners varies the hashrate, which in turn increases/decreases the difficulty, which in turn makes mining cheaper/more expensive. But I agree that the number of miners alone does not make mining profitable, I think the author was referring to hashrate.

0xbitcoiner

bitcoin

Is Bitcoin Mining Profitable ?

> Mining profitability depends on the hardware model, price of electricity, price of bitcoin, and the **number of miners** on the network.

This seems to be a mistake. The profitability of mining isn't influenced by the **number of miners**, but rather by the difficulty.