Genesis mining has been here for a long time, and I believe that most newbies to cryptocurrencies have tried its cloud mining services. Most people just do it for fun, but some people do it for the money, and usually they won't get any.
They are one of the few, if not the only one legit cloud mining site. Even hashflare has gone scamming their users. I would trust them to not fake mining, not steal your money, but i wouldn't trust them to make a decent return on your investment.
If cloud mining was indeed as profitable as some people say, why isn't genesis mining mining themselves? Think about it.
First of all, it's a pretty damn shame that you consider genesis mining to be "one of the very few, or even the only legit cloud mining site". And second of all, you are contradicting yourself in your own post. Genesis mining has refused to show actual proof of them being a large player in this market, and that for quite some years now. Them paying out for a long time doesn't mean anything beside the fact that they have enough noobs investing their money in that shithole. As long as noobs do so, it means there is a constant flow of fresh money coming in that they can use to pay out people. Open your eyes and don't consider them to be legit just because they are paying users, and that they aren't running with people's money. As I said before, they don't need to scam (while they in reality do so) people off their funds directly.