The contribution comes from their house edge. Look at the dice game, base return is 99.0, then they take 50% of their profit and stick it in a progressive pot. That's no different than any of the 99% dice games for the average player, there's just an additional and optional aspect of the game that some might find fun.
They're taking 50% of their *expected* profit, right? Because even if the players are lucky and the site has a losing week they still put 0.5% of the total wagered amount into the progressive pot.
My proposal is that they should offer an opt-out for the player, where instead of 0.5% of their bet going to a progressive pot, it is considered as bonus on their stake and so if they win, their payout is approximately 0.5% bigger than it would be if they hadn't opted out.
The fast setting on slots plays about 2 games/sec, 5 open tabs would be the equivalent of my bot.
Couldn't you run 5 bots? It depends on the sync issue you were hitting - is it per user? If so, running the bot as 5 different users would fix that.