In my opinion, the player must first be able to sufficiently identify with what the developer is explaining in their system in terms of why it must work. Every player sees something different from the next because all have different levels of understanding math in general and this is most of the problem. If the player can't fully interpret what to do, when to do it, why to do it, and how, then the system will always be a failure. Then, there's the money aspect which is the biggest problem of 'em all. Stack made a very good comment above on how playing all the combos will require more than a box hit to cover the money spent in the even of a hit.
I've been saying the exact same thing, Stack. Even more so, when not enough combos are played to secure a good boxed hit within a certain amount of plays, the player will still need a str8 hit to cover the real time money expenses. This is where the other thing called balance, which I've also been stressing, comes into play. When a player is truly on their game and understands full well what's going on, they have no problem spending the right money to ensure the correct hit to both recover and make money. Stack actually mirrored what I've been saying about players getting lucky that one good time on a str8 with very little money and then not being able to even come close to duplicating it again.
In fact, these situations are only going to be amplified in the coming days because people really believe that getting something for nothing in a game like this happens frequently. Luck happens, but not to the same person in the same fashion frequently. Luck is never consistent, but it's appreciated when it does visit...and people are satisfied with that. Problem is that you can't know when or if luck is coming back. Skill separates the men from the boys and the girls from the women...and also let's you know when it's time to play and win. Skill is extremely dependable. I say that with respect and within reason of the player's proficiency.
As I said before, if you really wanna know if something works, just follow the numbers: how many numbers, the cost, how many days played before a hit (if any), then subtract the amount of what has been spent from the amount won on the hit. This will let anyone know if what they're watching is worthwhile...everytime. I can tell you right now that based on the average amount of what 90% of people want to spend here, they better hit boxed within (4) plays. Numbers never lie.
L.L.