Hey, that's *me*. I'm the guy who makes Teensy.
First, thanks for the compliment. Really, the thought does count.
Indeed dev boards like Teensy do cost more than hardware that's subsidized by semiconductor manufacturers. They also cost more than Chinese clones. Those folks don't spend anything on software development, and they deflect all tech support and even some customer service back to the name-brand websites where they copied designs. Likewise, big semiconductor companies only put significant effort into supporting engineers at major corporations who are likely to design chips into high volume products like cell phones.
Projects like Arduino and Teensy are about helping ordinary people. We really do put effort into making things easier to use and we do respond to help individuals. We do invest a lot into software development that's aimed at allowing novices to achieve their goals. Obviously it's not possible to hand-hold everyone through every project, but the non-engineer user experience is dramatically better.
The simple reality is that costs money, especially ongoing software development as these 32 bit chips become more advanced and people wish to utilize that power for awesome projects. Name brand boards, where sales does fund software and documentation development will always cost more.
Software development means much more than just the tools. For example, years ago I wrote the FreqCount and FreqMeasure libraries, because all other exampls and Arduino libraries at the time has subtle timing errors. Since then, numerous people have wanted to measure 2 or 3 frequencies. Just a couple weeks ago I wrote a new FreqMeasureMulti library (released under MIT license) which uses the more advanced timers with input capture on every channel to allow simultaneously measuring up to 8 different frequencies. *That* is the type of software development which sales of boards like Teensy funds. I try very hard to keep costs low, but funding ongoing open source software development does cost something, which is necessarily reflected in the price of the hardware, since the software is all distributed for free.
There are many "Arduino Haters" in the world, and much of their frustration seems to be based on the high retail pricing for dev boards. Indeed, if you're an experienced engineer who's capable of developing all your code from scratch on bare metal, even things like filesystems and USB & networking stacks, then the idea of paying anything extra for well tested and easy to use software probably seems utterly silly. Paired with a simplified feature-poor IDE, it's maddening. But it really takes a special lack of human connection to refuse to see how easy-to-use platforms could be valuable for less experienced people, let alone utter beginners.
Of course, nobody uses boards like Arduino or Teensy in high volume products. Comparing costs of dev boards to the actual chips from distributors is silly. Sometimes it does make sense to embed a dev board into low-volume or pre-production units, especially if that lets you start selling and shipping sooner, but when volumes increase, of course you're not going to buy dev boards at high volume.
Teensy does use a proprietary bootloader. That's a business decision for a small company within a large marketplace with massive Chinese cloning. It's perfectly fine to object on philosophical grounds. The market is filled with lots of alternatives, much like how you can install Debian instead of Ubuntu. But bootloader corruption isn't much of an issue. Perhaps you're unaware that 32 bit Teensy uses 2 separate chips? You can't overwrite or corrupt the bootloader on the other chip, no matter what part of the main chip you overwrite. It really is a solid design, which has proven itself in real world usage over the last 3 years, by many thousands of people of wildly varying skill levels.
If you took the time to read all this, I hope you'll at least be able to appreciate that a tremendous amount of open source software development that many people take for granted is indeed funded by the sales of more expensive name-brand dev boards. That doesn't necessarily mean *you* should buy one, but a little recognition that lots and lots of widely used open source code is written by relatively few people who are funded by creative business models would be nice.