How are developers incentivized to make decentralized Dapps?

I've commonly seen things said like "Ethereum can be used to create a decentralized Facebook". I understand how this can be done, but I struggle to comprehend who will do it. Who spends the time to make this, and who spends the time to maintain it day-to-day like bug-fixes, moderation, handling reported content.

Is it going to be individuals posting bounty's to get this done? Or will it be primarily relying on open-source dev's goodwill? Or is there supposed to be a token for bug-fixes, and a token for reporting something, and a token for login, etc.. that developers can.. sell?

As you can see, I am very confused about this.

Submitted January 10, 2019 at 06:53AM }
via reddit