There are perhaps 3 main rewards for writers:
1) The personal enrichment that comes from forming your ideas and writing about them.
2) Being able to share your writing and attaining positive* public feedback (in the form of praise, prestige, admiration, notability and reputation).
3) Making a living (or in some cases a fortune) from doing something you love.
Not every writer has number 3, but every writer can have numbers 1 and 2 (in the case of 2, assuming they're any good).
For those for whom number 3 is a bonus and not to be expected, and for those not being paid by newspapers or magazines, 1 and 2 can still be obtained either through writing books and attempting to get them published or through writing Blogs.
If we assume the pleasure of 1 is steady irrespective of 2 (that certainly is the case for me), then a writer has an interesting consideration regarding number 2. Blog writers like me are not being paid for Blog posts, but we can share information to a wide-ish audience, and obtain positive public feedback.
Playing around gracefully with hypotheticals, as I often like to do, I wonder what sort of value I (or anyone like me) would place on number 2 in all sorts of scenarios. Suppose there were 50,000 impressed readers reading my Blog for free each week vs. 50 super-duper impressed readers who would pay £2 per week to read my Blog (I doubt it - but humour me). What's better for the writer - all that adulation and no money, or 0.1% of the adulation and £100 per week? What about 100,000 non-paying impressed readers per week vs.100 super-duper impressed readers who would pay £2 per week to read my Blog (earning £200 per week for me) - which of those is preferable to most writers, or is it fairly evenly split? Perhaps the mass adulation would be worth losing £100 per week for but not £200. I don't know. There are lots of other factors too, and I haven't given them a lengthy consideration.
In real life terms, though, how might my Philosophical Muser Blog fit into the above consideration? Let's start by asking the following question. Suppose you're a budding writer - would you be happy if you wrote a book, had it published, and it sold 4562 copies?** There are, of course, a lot of variables attached to that question (even aside from financial ones). When it comes to expectations, if you're Lawrence Krauss or Francis Collins then 4562 copies sold would be a flop. If you're JK Rowling then 4562 copies sold would be a disaster. If you're an unknown sending off a book you're not that pleased with or bothered about then 4562 copies sold would be quite a success. If you're an unknown who has written what you think is your magnum opus then the disappointment of only 4562 copies sold may outweigh the pleasure at getting a publishing deal.
The number 4562 is not insignificant in my deliberations. My Blog reader count is 188,488. If we say that each hit has an average time of 2 minutes, which accounts for those who spend less time per hit and those who spend more, then that amounts to a total of 9124 hours for my aggregate readership. If we say that an average regular size book takes 2 hours to read, then 9124 hours of Blog reading is equivalent to the reading time of 4562 books. Thus, if I take into account only the information shared and the readership interest, then my writing this Philosophical Muser Blog has been roughly equivalent to writing a book that has sold 4562 copies.
As it happens, I am writing books as well, but haven't yet reached the stage of attempted publication. Until then I can dabble in my Blog writing. I wanted to write this to encourage fellow Blog writers, and others writing pro bono and au gratis - if as yet you're happy with the rewards of 1) the personal enrichment that comes from forming your ideas and writing about them, and 2) being able to share your writing and attaining positive public feedback - then what you're doing has some of the rewards of writing a book and having it published, so be encouraged to keep up the good work.
* That's not to say negative feedback isn't valuable - but if we are being truthful, no writer really likes it.
** You may say selling 4562 copies has the added benefit of enhancing your future chances of being published, but consider it may have the opposite effect. Having a first relatively unsuccessful book published might be a springboard to future success, but equally its relative failure might put off any future publishers.