I am not sure if your post was directed at me but
1) The former problem with the Frankenstein slot is a FACT, not a theory; it's just that we do not know any details about it. I used it to illustrate that ANYTHING can happen even with slots from reputable providers. Whether it was intentional or unintentional, we can only speculate.
2) I think the math behind variance and how much money the casino makes (and therefore how much money the player loses) is quite important and just as interesting as the math behind the mechanics of slot - actually these mathematical aspects must be closely related in slot design.
My point was that at one end of a spectrum you could have a slot that had 0 variance. You bet 1 EUR and you win 99 cents back. That is the best money-making machine for a casino that can be. And it has 99 % RTP

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yes you are correct this would be the ultimate from our point of view but then no-one would play and therefore we would not make any money at all.
By a simple logic it would seem that the higher the variance, the more advantageous a slot is for a player. But unless I am mistaken - and I would be happy to hear an expert comment on this - the profit of casinos does not equal the house hedge. It is actually much higher because the player, unlike the casino, does not have unlimited funds. So the player often busts before getting the bonus round on slots, for example.
No this is not correct, our GROSS profit is the house edge - although this will depend upon the volume of bets on different games that all have different RTPs, but generally the Gross profit is the total amount played (turnover) multiplied by the average Margin or RTP
So if a slot's variance is too high, the players may - in theory - never (or it may take them 50 years, which is "never" for all practical purposes) reach the 100 000x bet bonus round (an extreme example) and the casino may make much more money from such slot than from a slot with a lower variance.
This is true only if you are talking about one player and his/her big win does not hit early. This is the beauty of variance and, as Trancemonkey has been explaining, because each spin is an independent and random event it is just as likely to hit on the first spin as it is to hit on the 1,000,000,000th spin, it is all down to probability. Therefore it follows that from a casino point of view when you have 1000's of players playing the same game those bigger hits come more frequently even though more players lose their balance more quickly due to variance and volatility and therefore the casino edge is still the RTP. The ONLY way that we can make more money is to get more players to play and retain the ones that have played with us previously.
I think it is called "hold" what the casinos actually earn as a profit.
Casino Hold is a theoretical value and cannot be used only as a guide but cannot be used to calculate anything other than between when a casino opens and a casino closes. There is always money being deposited and not withdrawn by players in a casino and you can never know whether the money that is currently invested will be withdrawn, played to extinction, partially withdrawn or even when either one of those two events will happen or if indeed it will ever happen. For example we had a player last March that won $20 with his No Deposit Free Spins, the money was left on his account until a week or so ago, the player came back and then turned this into $30,000+ and then withdrew. So when can we calculate our hold? Daily? Weekly? Monthly? Quarterly? Annually? This is the reason that all listed Gaming Companies report revenues based on Gross Gaming Revenue which then trickle down to Net Revenues and EBIT figures
And I would assume that some kind of a perfect balance between variance and the casino's "hold" is the most important financial aspect in slot design and that these are the games on which the casino makes a profit while giving the players the feeling (actually the experience) that they have a decent chance of winning something worthwhile from time to time.
The basice difference to players between high variance slots and low variance slots is that a player can hit a big win in one go on a high variance slot and therefore only need to get lucky once in a session. To win with lower variance games then you have to be lucky over a longer period in a session to beat the RTP. However the base line for us as Operators is that it is ALWAYS the RTP that is important and that we provide games that have a mix between different volatilities to cater for a wider range of players in order to retain them.
And I think that this is the main reason why players like some slots much more than others, even if they have the same TRTP.
My question is: Am I right in assuming that a casino makes a higher profit from slots (or any casino game for that matter) than the house hedge?