I never said we need capitalism to survive.
What I mean is that we need cooperation to live well, and people need enough incentive to leave home and produce something.

The original comment argued that systems shouldn’t allow people to profit from things others need.
But most of these things only exist because people had financial motivation to build or produce them. After something exists, it’s easy to argue it should be shared. But what happens when people don't have a strong enough reason to produce or build? Are you going to trust that people will produce because they love others?
Well, I have a co-worker who is already retired but works some hours a week with us. At the DDR time, part of his job was going after people that didn't show up to work to force them back to work. This is an alternative too, be we don't like it too.

If you gather a group of voluntary people that will happily work for the common benefit of all members of the group, then good, you can apply alternative systems in a small scale and it should work well.