I am afraid such happiness would destroy us. Or make us a docile sheep with no ambitions. At least part of humanity accomplishments is because challenges induce chemical imbalances, they take you out of your comfort zone.

I would like to add that this science already exists for thousands of years in such sophisticated form that it does not require external chemicals but rather focuses on enhancing what our body can naturally produce.

Imagining this gives you a bit of entertainment, but experiencing this makes imagination a childish game :)