Welcome to part 2 of Crypto Scams to Avoid. If you have not read Part 1 yet, you can find it here: https://www.mobilephoneminers.com/post/crypto-scams-to-avoid-part-1-free-airdrop-dapp-scam
First off, the only free mining is any you do on your own hardware whether that be a phone, a GPU, or an ASIC. The only cost to you is power and if your not mining on your own, a pool fee. Any pool that is reputable should not have a fee over 1%. If your getting charged crazy gas fees because they based off ETH, then find somewhere else to mine.
Now that I've explained what real mining costs are, lets look at some of these "free" mining sites. The first thing I notice is a bunch "giving away" a certain level of mining for "free". For Bitcoin this is usually 100GH. That might sound like a lot but let me put it in perspective. A modern ASIC miner for BTC can do 100TH (That's 100 000 000 000 000 hashes) a second. That translates to about $20 USD a day right now. Let's put that 100GH into perspective. That's 100 000 000 000, or 1000 times less then a modern ASIC. So as far as the amount of income earned, you would be looking at about .02 cents for an entire day.
That would be ok if that was all there was to it. But of course that's not the end of it because then how would they make any money? There are several ways and combinations but they basically come down to these things. Making you jump through hoops by placing your earnings in other areas before you can withdraw. For example, anything you mine is put in a hold area, then you have to do something to move it from the holding area to your wallet. Making you find other referrals before you can withdraw what you have earned. It could be 3, 5, 10 or more people you have to get to sign up with your referral code. Suck them in to making 2 cents a day and basically just SPAM the hell out of everybody for nothing. Even then, after all that, when you finally manage to do all this they will most likely hit you with a ridiculous withdrawal fee and very high withdrawal limits so you can't cash out for months. Quite frankly most people won't go through all this garbage for just a few cents a day so they hardly ever pay out (If ever). And they are probably serving you ads and profiting from you off them as well. Even if they don't have ads, they are still making money because guess what, they are still getting most (If not all) of the mining profits and a constant supply of new recruits to promote them. And some people will buy the packages they will most likely offer and profit from that as well (from the sale and again from the high withdrawal limit). And if they are really shady, you might not really have anything in your wallet at all and it's just a program spitting out a bunch of numbers to make you happy.
So go mine the free coins on your phone, from the genuine companies trying to promote a better way of mining. Mine this next generation of coins as much as you can. Be patient and hold for 2-5 years and the top projects will be very rewarding. You already touch you phone a 1000 times a day, do you really want to kick yourself 2 years from now because you couldn't be bothered to touch it a few more times? I hope I see you at the finish line with lots of money in your pockets.