Altruism require giving away resource with no expectation of benefit. So in short, it is sucide of the individual if practiced to extreme.

A more substainable form is voluntary exchanges in which individuals exchange good and services for their percevied benefit. That's cooperation based on "stratching your back, you stratch my back".

Also note that individuals are what composed of groups. They are the smallest building block of society. Focus on them, and you benefit the group. The ideal situtation is that you would never need to sacrifice an individual for the whole group.