Many questions on this topic around here, but didn't find this particular angle
Background: Sending any information of value with HTTP and through HTTPS is a bad idea (in the rare case a respected website would give you that option). The ubiquitous establishment of SSL has unfortunately been a bit slow, in my understanding, as the high prices and mess with certficates for the low/average experienced website admin. (maybe initiatives like this will hurry up that although? https://letsencrypt.org/)
Question: But how insecure is actually the use of HTTP for e.g your personal whole "not-so-important" Wordpress blog, if you are aware that your passwords flows uncryptated and thus only access sensitive parts of it on secure known networks (e.g your home trusted WP2-SPK wifi)? (sitting on a "public" (cryptated or not) wifi/LAN where you don't trust the hotspot and/or the other connected users is a own security story, exclude that the user is unaware of the basic secuirty risk in this case)
Being sure no one snoop of spoof you between your computer and router, how secure can you estimate your data to be over HTTP? I haven't understood what potentially could happen on the way between your router and the server, even if you secure "your end", what stuff could happen on the long travel through the web to the server?
Is having your hobby blog on HTTP "good enough" (considering your generally good at using unique passwords etc), or should a VPN be used at all times in the HTTP+password cases?