That's my approach as well.

Mobile book bundle? I don't typically do much mobile outside of the browser, but I'll grab it just in case I get the itch.

Security? I don't make a living there but it's always been a fun hobby of mine. Sold.

Cryptocurrency? Not interested in investing, but I might as well get a deeper dive on blockchain et al.

Usually 10-15 books for the price of one? Sign me up.

Honestly, the price of a book doesn't matter to me. I'm far, far more constrained by time than money. Give me 15 free books and most of them are just going to sit on my shelf for a long time.

Unlike reading a novel, I find reading technical books don't really "stick" unless I invest significant time, right then, using the language and actually trying out what I'm learning.

It is akin to my experience with learning an instrument -- it is easy to get sucked into buying books and watching videos, but it does zero for my ability unless I'm actively playing and struggling with it.

Some fair points but if like most people you can spend only so much, getting more books for that same much is useful: if you have 15 books of a same subject matter you can rather easily compare them with a quick skim and devote significant effort only to the best ones, or pick only the best parts from each. Otherwise you can easily end up spending weeks on what only when you'll have gained more experience you'll realize was a worthless crappy book.

Even if you're careful in checking the reviews before buying, a lot of technical books have only few, questionable ones, and sometimes there are remarkable books behind them nonetheless!

I like having a library that I can flip to when I'm bored and want to do something productive.

Same, I usually just buy in order to encourage more of these bundles. I bought this one without hesitation, even though I'll probably never read any of them.

Same. I figure I'm building myself a pretty handy reference library for a fraction of what I'd spend on Safari... now the only way O'Reilly is offering these ebooks directly.

I really learn much better from a paper book, so I use Humble Bundle as a cheap way to preview the books! It is still worth 15 bucks!

Same, development books and electronic books. There was also a mobile dev book and java bundle recently.