As majority said it's not worth it as of the moment but if you have the way to sustain your mining expenses and you believe to the coin you're mining currently, you shall reap what you sow. With your condition OP, you're in good hand that your electricity is cheap enough to sustain it. If I'm on your situation, I'll definitely won't stop mining but also depends on the coins you mine. The strategy of most right now is to mine those coins that has lesser difficulty and not yet on exchanges.
The only real way to make a big profit is to mine new coins that aren't available on exchanges yet but that is very risky.
Correct. High risk but high reward, not for the weak hearts.