Please take with a pinch of salt.

While I do believe OP (i've met seniors like that too in the past), this is not a general description of all liti lawyers as a whole. I've since found a firm where my seniors are pretty decent people and my hours are good. This also means accepting that you'll never be a millionaire, but in life you can't have your cake and eat it too.

My boss is pretty humane and always asks if i have capacity to take on a case - and saying no capacity does not impact my pay/progression/ect. I don't OT on most days. When i do (during big trials about 3 times a year), i can generally take time off thereafter.

The anxiety is something you have to manage in life. I worked in-house full time while doing my masters (2 years) and trust me when i say that the anxiety doesn't go away. When i was in-house, i had to handle a lot of shitty politics and truly incompetent bosses. I reported to a general counsel who was neither called nor spent any time working for a law firm. His background was in project management. But you know, connections get you places in the world. Keeping the bosses happy whilst protecting the interest of the company is not as easy as it looks. The anxiety doesn't go away.

I was told this once: how much you are paid is proportional to your ability to handle stress.

This is very true. Don't expect that moving in-house would automatically mean a less stressed existence.

To the OP. I was from a small firm liti department and went in-house directly (with a major pay bump). It is possible. Try applying and sending your CV to legal recruiters (a dime a dozen on linkedin). They are always on the prowl for applicants.