To be pedantic, I'm not personally paying for OpenTimestamps transaction fees. There's a community fundraiser for that:

Geyser | Bitcoin Crowdfunding Platform

A Bitcoin crowdfunding platform where creators raise funds for causes, sell products, manage campaigns, and engage with their community.

and the calendars themselves accept funds directly to their wallets. Last time I pushed for donations was in January, and I got enough donations to last until now (most donations, by value, were not sent through geyser). I'll probably run out of donated funds again in another 2-4 months. FWIW I share the funds donated to my calendars (and through geyser) with the other calendars.