I think everything is conditional. Being 'nice' is not an existing thing.

If being nice doesn't offer you anything, you won't be nice.

For example, a 'nice' person probably feels good inside their body if they do something nice. Therefore, they are acting nice, because it makes them feel good. Conditional.

If it didn't make them feel nice, there'd be no stimuli that incentivize the act of being nice. Therefore, genuinely kind people do not exist, only people who feel good when they do nice/kind things.