First, salaried rank and file software developers on average certainly don't make 300-400k per year. Those working at Silicon Valley FAANG companies still account for only a minute percentage of software developers in the US and certainly in the world.

How that is supposed to constitute a bubble is beyond me.

Then, payment for work isn't (or shouldn't be) about (perceived) equality and it isn't about compensation for suffering or even mere inconvenience either. It's about the value created by the work, which is why the work being hideous or insanely long work hours shouldn't be contributing factors that justify a high salary. Now, this of course is an idealistic notion. Often work is still valued in terms of time wasted instead of value created. Moreover, in the case of some not so well-paid but still important jobs the salary attached the them often is only tenuously related to the value created.

All that said, while probably few professions will be able to match the leverage and hence the value created through software development in the near future, perhaps the more reasonable hours and better work environments in software development should serve as a model for other work environments and industries rather than as an indicator that something's amiss.