No, that's a gamble, that you will get more benefit than you pay for. Those that don't buy insurance gamble that they would get less than they would have paid for.
You are not buying insurance as a gamble, but as protection against ruin (sometimes called "gambler's ruin"). You typically know that it is a bad gamble, but still of value for its protection against ruin.
I guess that comment was off-topic.
At 18 months?
Obviously the insurance model I gave is a simplification. But sure, by 18 months the child has already learnt about social relations, at least within the family, and already knows the benefit of doing things that please his parents.
and how does this explain the chimps helping?
I'm not an expert in chimps. But they are a social species, albeit not nearly as social as humans.
Personally I believe it is a by-product of a social species behavior.
I agree. But that doesn't contradict it being learned behavior.