Those numbers are real, no doubt about it but even if you potentially have the skills and knowledge to compete for those positions, your odds of getting such a job are still incredibly slim. If you are young, immensely talented(for the lack of a better word), and in a location near the job offering, then yes, there's a chance. But even giants such as FAANGs will have their doubts when you're 30+ and on the other side of the planet, even if your profile fits the needs of a senior engineer better than the youngsters next door, because they are well aware that at this point in your life, your priorities are increasingly becoming children and elder family members and it is incredibly likely for you to pack your bag and leave the moment something goes wrong with your family on the other side of the planet. And with such salaries, you'd be perfectly capable of doing that in 6 months, just when their investment is starting to pay off. Strictly speaking, you are looking at a very small subset of a subset that was tiny to begin with. For most people that doesn't happen even in dreams.

Unless you're doing interesting things at google for that 300-500k, 100k to work on OSS problems seems immeasurably better to me especially because they don't have to live in the bay area.

100k in pretty much anywhere but the east or west coast may as well be 300k.

> I would estimate Sr. or better is possible for someone who is able to independently run a OSS project.

I don't believe that's a correct assumption. It's been a while but: https://techcrunch.com/2008/01/01/zed-shaw-puts-the-smack-do...