Doesn't need to be 50k to prevent spam even 5k sats would probably be enough, a spammer could spend 50k or even more to spam in a single relay, but then all the bots would be banned after a short time and he would have to spend again. I would see a zap to reply as a way to prevent troll comments and I think it would be a cool feat, as long as we have options we will use them the best way.
Your client could auto-zap it when replying if you have a built in ecash wallet or NWC set up. nostr:npub1h0uj825jgcr9lzxyp37ehasuenq070707pj63je07n8mkcsg3u0qnsrwx8 charges you 1 sat to send a DM and it seems to work great. I’ve only sent a couple messages though.
If you only read from paid relays, you’ll miss out on all the notes from people that can’t afford to pay for the relay. Paying 1 sat to post a reply is much more manageable than paying 50k sats upfront for a relay.
Discussion
I just threw out 50k cause that’s how much I thought nostr.wine was. I just checked and current price is 18,888. I’ve happily paid for nostr.wine, but I still read from free relays cause I know many people can’t afford to pay for nostr.wine and I still want to read their notes.