On Having 85k Sats and a 15% Fee

you can also use the ! pay command or the wallet screen's send button to just send money with no treechat fees at all.
treechat fees are only for upvalues, the idea is that what you're really paying for when you upvalue is the community's attention. your upvalue brings the post to the top of the treechat feed where everyone can see it

The 15% would probably also include the operational costs for hardware and servers.

Give it to me …