For a nostr client to cover expenses and salaries it really wouldn't take many people to subscribe. You need scale at the network level to make it happen but it's VERY doable - just a numbers game. 

Don't forget, not all subscribers are the same. Some are happy to support the products they use at different levels. We cannot assume Twitter paid subs are all paying the same price that would be insane. Companies paying to subscribe are likely accessing other services. Startup rule #1, scale pricing.   

 What is the incentive for running a service for free? None. Copycats exist, but never last. A client is more than a set of features, there's brand, there's loyalty, there's ongoing support. If features were all that mattered Apple would not exist. 

I don't see subscriptions as charity. You pay for what you value, for whatever reason. 

We do need to scale to be able to pay full salaries though. Just as some play math:

$9 sub would require 1388 paid subscribes to reach $150k annual (decent for solo developer, 2 if you take a massive pay cut). This assumes a 5% conversion rate on all users (very generous I think). So let's say 1500 subscribers. This is about 27-30k active monthly users on the network - a 3x from where we are today. So.. not an easy feat, but certainly achievable. This doesn't include zap splits, donations, marketplace fees, any of that. Subscription-only would tough at this point, so I think it has to be a combination of things, or just work to scale the protocol. Scale solves a lot of problems (hopefully more than it creates).  

 I think I made an error in assuming 10k monthly users, it's probably a lot higher already. We are at 10k daily, 20k weekly, probably 20-30k monthly already. 

 Una estrategia de referidos interesante sería

Pagar una subscripción que te de privilegios en el cliente como funciones PRO, con un mecanismo de que si traes a un referido que pagué la subscripción te realicen un porcentaje de Cashback,

Habria incentivo de traer usuarios.

nostr:nevent1qqsqul9jew2kg3e4yr95dfwgtm8p7huj0hpxhn6m82t0zngy3d76k3qpzpmhxue69uhkummnw3ezuamfdejsygqmcu9qzj9n7vtd5vl78jyly037wxkyl7vcqflvwy4eqhxjfa4yzypsgqqqqqqsj370f9 

 Una estrategia de referidos interesante sería

Pagar una subscripción que te de privilegios en el cliente como funciones PRO, con un mecanismo de que si traes a un referido que pagué la subscripción te realicen un porcentaje de Cashback,

Habria incentivo de traer usuarios.

nostr:nevent1qqsqul9jew2kg3e4yr95dfwgtm8p7huj0hpxhn6m82t0zngy3d76k3qpzpmhxue69uhkummnw3ezuamfdejsygqmcu9qzj9n7vtd5vl78jyly037wxkyl7vcqflvwy4eqhxjfa4yzypsgqqqqqqsj370f9 

 I think I made an error in assuming 10k monthly users, it's probably a lot higher already. We are at 10k daily, 20k weekly, probably 20-30k monthly already. 

 Una estrategia de referidos interesante sería

Pagar una subscripción que te de privilegios en el cliente como funciones PRO, con un mecanismo de que si traes a un referido que pagué la subscripción te realicen un porcentaje de Cashback,

Habria incentivo de traer usuarios.

nostr:nevent1qqsqul9jew2kg3e4yr95dfwgtm8p7huj0hpxhn6m82t0zngy3d76k3qpzpmhxue69uhkummnw3ezuamfdejsygqmcu9qzj9n7vtd5vl78jyly037wxkyl7vcqflvwy4eqhxjfa4yzypsgqqqqqqsj370f9