Yes, it makes them happy, actually the feeling of happiness arises because of a misunderstanding regarding their perspective on the bonus, I am sure that they feel happy because they think that the bonus will give them a number of wins, when in fact it is still a "possibility", in the sense that the bonus comes not to give you a win, in this case the casino is very smart, the dealer knows about what can trigger joy, hope and confidence so they provide bonuses as a facility, actually it is not to give free wins to gamblers, but nothing more than just to increase the gamblers' hopes for victory because the casino knows that when a gambler's hopes and beliefs increase, the possibility of various more aggressive actions will increase.
It seems that this is a case that often happens, my friends and I when gambling slots are very happy and sometimes even excited if we succeed in getting free spins, especially if the bet amount is quite large, that's the pleasure that is felt at the beginning because it often happens where when we get free spins it makes us happy but the results make us annoying, I have experienced this and if I tell my friends about this it is very ridiculous even to the point of laughing out loud. Moreover, we actually already know that the final result will most likely be disappointing, and what happened to my friend was happy to get free spins, but we laughed out loud when the results were disappointing.
I think here the dealer is indeed quite smart because they can influence the feelings of their players to become more interested when they have failed to win with free spins, because not a few gamblers continue to gamble when they fail to win even though they often get free spins, but this interest will only make gamblers more aggressive in their actions as you said.