Yes. Humans can not/should not live alone. If everyone built things for themselves, humanity would be so far behind. If I cook, you build stoves, someone farms, someone builds houses and someone generates energy. But if we expected a farmer to give out his yield for free, would he do that? 

A farmer's goal is to farm as much as possible, sell his crops, build a house, buy a stove and hire a cook. 

That's why, someone who is building a Nostr client needs to hire a frontend developer, a product manager, a designer and a quality assurance person. We need all these to succeed. Without a clear business model, we can't do anything of these things. I would say economic incentives are the biggest missing thing in Nostr. 

Donations don't scale well. It also misaligns incentives.