I think you are thinking like a basic Faucet user who just want to make money ....
How shall I put it?
If it were for the money, I would have left your site roughly 10 minutes after I signed up.
I believe 99% of users on your site aren't in it for the money, simply because in calculation of amount of time invested to value cashed out your site pays less than 1/10 of other sites.
But users do the math and where they don't expect much money from this, they won't invest into the site either.
I mean, what's the point of paying almost 45,000 sat for 1000 crystals that are entirely worthless plus 10 HP?
It will take a user roughly 2 years of uninterrupted virtual mining to get those 45,000 sat back and then that's a value of less than $2.
Personally I currently have almost 9,000 crystals and not the slightest clue what to do with them, just the opposite, just by doing missions I'm getting more crystals than I can use in virtual mining even if I never sleep and keep virtual mining going 24/7.
Why would I pay for more crystals? Why would I pay $2 just to MAYBE get $2 back in 2 years and from then on 5 cents more a month?
This is the crypto world, we can't even be sure whether or not there will be a crypto world in 2 years from now.
Furthermore, for the fun factor of a game ....... well ....... it's just not for me, I don't like war games, never have, never will.
I prefer construction over destruction, i.e. I LOVE games like "Legend of Zelda".
That in combination with not expecting anything of value out of the game is why I've deleted my VMP.
Anyway, if you're convinced users will love your game so much that they are willing to buy cards, then put your money where your mouth is, offer users the reverse option of selling cards for the same amount it costs to buy them and leave it up to the users which way around they prefer.
That's the easiest possible way to find out whether or not your users like the game.
Offer users to sell 1000 crystals plus 10 HP for 45.000 sat and be prepared for almost all users on level 18+ cashing out 400,000 sat by tomorrow.
Glad you remember me though ...... looking forward to you getting back to me on Skype as you said, once you're done with this war game.