It's not a scam - but yeah, nothing is free either, right? :-)

Conventional computers are just not that efficient for mining. I mean, yes my laptop is like 5 years old, (it is still faster than average according to cpubenchmarket.net) but even when I ran the benchmark within MinerGate, I got a 4/5 stars, and (assuming I pay no power, which I do) - I could only make up to 50 USD... per year! (but w/ having to pay the power, as I said, I'd be running a deficit.)