I think it must be an accumulation of stimulating factors that make certain types of bets seem attractive to us, based on our personal tastes.
What do you think?
I think a little diferently... I believe that every gambler is motivated by a small winners in order to have more motivation to continue playing with regularly, and it does not need to be a big prizes for that.
I see that casinos, whether physical or online, allow us to have small wins occasionally to keeping us motivated and with that feeling of "next time the prize will be biggest", but without us realizing it our money is completely drained.
I don't see this as a bad thing, if its demonstrably fair... the game was made to keep us entertained and they do it very well. So it is the player's duty not to let themselves be consumed by this desire and to manage their finances wisely.
That's how we are being controlled, and maybe you are right specially in online casinos, if they see that you might be a new account and so they do make us win and feel that everything is good and that we can replicate our winnings.
So there might not be a good answer to the OP, still up to the individuals on how they are going to response. As this is a human stimulus, so others might react different if we are in the positive or losing a lot of money already.