I think people over-complicate this. Toxic maxis are basically the same as toxic-anybodies: they enjoy being dicks, and so they are dicks. And then, just like all dicks, they find a way to justify their behavior so it seems to be the expression of some deeply-held values.

Here's an experiment: if you run into a "toxic maxi" that you know IRL, ask yourself if they're toxic in other aspects of their lives, too. I expect you'll encounter zero examples of good, thoughtful dudes who are simply so inflamed by the principles of btc that they turn into raving douches in this arena only. Even online you can see the evidence for this wider toxicity everywhere.