121 likes, no question on Nostr today.

A like is to me evidence that someone saw and agreed that the post should be seen. As much as 21 sats is a spam deterrent and has opportunity cost, likes represent for me even more opportunity cost spent in the form of time. The caveat here is I'm assuming likes come from real people whose time is precious, hence the "on Nostr today" qualifier.

What makes the conversion factor hard is that likes are nothing like currency. They are not fungible and cannot be sent on.