Basically there's not many people that would feel comfortable putting $800 in one go at a slot machine, but many end up doing so by putting small notes, $1, $5, $10, at a time, and then trying to recover loses, etc. If you sum up all that they will realize they paid more than $800 even though they wouldn't have done it in one go.
He must be quite rich and have a large initial capital if he wants to use such a large base bet, the casino will call the high rollers. It will be difficult to immediately get a high multiplier with just a few spins if he does 10x spins it has spent $ 8000 maybe players can buy bonus features and expect will produce very good results or at least achieve what is used to repeat the same thing until finally getting a big win because luck has approached him, and players like that will be treated very well by the casino because it is profitable for their business.