Going to a bootcamp shows you are just another good student, who can sit in a classroom for 10hours straight in a day, during 12 weeks, and get good marks.
When you are self-taught, you show that beyond your new technical skills, you have the self-discipline, and drive to learn and practice new skills from scratch, without someone holding your hand. This must be a skill that any employer would value highly. Employers would want their SW engineers to be autonomous, and have the self-discipline to initiate to keep learning, because with SW, you need to constantly learn if you want your skills to remain up to date. Teaching yourself SW is hard. If you manage to do that, the proof is there that you are passionate about what you're doing, because I don't believe it is possible to teach yourself SW without being passionate about it.
There are heaps of resources online nowadays to teach yourself SW engineering.
It's really about how much money you have. If you've got significant savings like I did, it makes sense to pay as time becomes more valuable than money in your life plan.
You also seem to think attending a bootcamp automatically precludes a student from being able to provide themselves with continuing education.
There are different motivations for people entering a bootcamp and some are looking for that paycheck. But again, that does not necessarily make them a bad SW engineer. And if those people would like to keep their salary, they will learn soon enough that they will not get very far with stale knowledge.
Don't get me wrong, I've met some brilliant and capable bootcampers, who I suspect would've done just as well or better outside of a bootcamp, but my point is that having a bootcamp portfolio isn't much of a signal.