Bugs are "High value" in different ways, you have to find the companies willing to pay highly. Most of the high payers are on bug bounty programs (like hackerone.com) and don't always give you ability to talk about bugs later.
Google is quite unique here, particularly given Chrome is paying easily 10x what Mozilla would for a sandbox escape. Apple is in the middle -- per [1] a "WebContent sandbox escape" would be $50k, but to get $250k on their scale you need to combine that with a kernel bug.
So if you want to optimise for "value", you have to pick the targets that are easier (still not easy, obviously).