Yeah, the tail emission pays miners. Nobody else has to run a full node, maybe you want to just to do it in which case you don't expect payment, maybe you do it because you have a lot of monero, in which case you're paying directly for your own storage, nobody is doing it on your behalf.

You're right, it takes too long to sync the chain. I'm not saying we don't need a solution, I'm saying your proposed solution is not the correct one. I think the only solution is to remove the need to keep spent outputs forever, and this being Monero, to do it in a way that preserves current privacy guarantees. This is currently not possible, you can do one or the other, not both. I think we will get there.

On the topic of syncing the chain, again it is perfectly possible right now to sync only from your restore height. This means the only people who are stuck syncing forever are people who have unspent outputs in old blocks. If you want a faster sync time, take your own advice and sweep to a new address into a brand new block, then you don't have to really worry about syncing forever, you get exactly what you're asking for, complete with reduced security, without forcing it on the rest of us.

Money is a storage vault and a medium of exchange. You can be fast and light without deleting people's savings. We just have to figure out how. Cash is not cash if I can't put it under my mattress and expect it to be there whenever I determine it's time to use it. Money that evaporates isn't money.

Users would need to churn their outputs or they can opt to retain the chain data if they wish.

Yes, that's currently how it works. We just opt to retain chain data more often than you'd like. If you want to, you can sync only from your restore height, if you want to churn outputs so your sync time is less you can do that. You get what you want, I get what I want, everybody wins. What you're proposing is already an option for you if you want.

There needs to be a solution, yes. Not your solution. I think 3-5 years is a great timeline, in time for seraphis and jamtis to roll out and significantly improve the status quo, and plenty of time for someone to figure out a real solution, such as a scheme that preserves complete privacy while allowing all spent outputs to be discarded by nodes. I hope it happens. But discarding unspent outputs globally, forcing people to do it across the whole network, is simply not an option.