Many of us probably don't need this enough that we pay for it. I could get by with just rust weekly newsletter for the news. Then there is the official forums if I need to ask a question. The main use I got out of r/rust (and now am hoping to get out of this) is reading and learning interesting things, perhaps answering a few questions along the way. Not critical enough to for me to pay for it.

This is in a sense a sad state of affair. But you are probably never going to get enough critical mass to build a community if you paywall it. All websites that use some form of paywall that I can think of started out free to build that critical mass.

An optional subscription though could be something. Maybe you get a special marker at your name as a bragging right that you are a supporter? A star next to threads you start? Something like that. Several sites pulled of that model (two comes to mind immediately: twitch, phornix (a linux news website)). LWN.net (also a linux news website, more in-depth though) is an interesting example: it paywalls it main articles for a week, then they go open. Again, it didn't start out that way though.

I don't know if the underlying software supports optional subs though, another option could be a simple paypal tipjar or patreon, but you likely wouldn't get as much that way.