Mining is not profitable in these days, if price of BTC reaches 1000 USD I think it becomes profitable again, but thats a big IF.
Nowadays, so many people says this. But, if that's true, how come so many miners are mining now and difficulty is still going up?
It's because they have no idea what they're talking about; just spitting out what they've heard from other people that seem knowledgeable. You're absolutely right, bitcoin mining is probably always going to be balanced so that it's on the line between being profitable and not. Even if the price goes up to $1K, more miners will come in and it'll get harder to mine blocks; you'll have to mine longer to get a block, making it balanced out again.
No, mining isn't profitable for the vast majority of the population. It's so competitive that being a profitable miner relies on many different variables: Cheap electricity, cooler climate, adequate start up investment and access to facilities, to name a few. For the average Bitcoiner that says "Hey I want to try mining", putting in a couple of Bitcoins on mining hardware will result in a net loss in profit.