The slot machine is set with a payout to give back a % over time There is no guarantee the machine will give you money. You can spend an entire session losing. If it spits back some money, it is paying you back part of the money you spent, but until you are paid more, you are not in profit.
ClixGrid is giving you money FREE......and is very much limited in revenues to do so, compared to a slot machine.
So yes the odds of getting a winning in CG are exponentially lower than that of a slow machine, but it is not costing you money to play.
To be honest, I've stopped clicking CG daily too. It is not a must. Considering I could make $5 in 1 day with tasks if I wanted to.
There are 2 things one person can do at this point when they are unlucky and not winning. They can keep on clicking for a free chance to win and hope that one day they will win, OR stop clicking CG. After calculating my winnings vs. my number of clicks to CG, it comes to 0.001 per click
They are giving prizes based on what they can give and how many people click the grid.