So I used to be VERY active on this forum... But about 2-3 years ago, I've been kinda disappeared.
Because I have spent all the free time that I used to spend on here to deep dive into churning circa 2021-2023.
I was late to the game, as those who churned 2016-2020 had a lot more bang for the buck due to gamification of the system.
To answer the OP question: worth is very subjective. We don't have all the same information and values.
To me, it's very well worth it. It takes about 10 mins to apply for a card and about 20-30 on the phone to cancel it. I've been getting pretty consistently 10% of my spend as points back (assuming 1 point = 1 cent). I just cancelled two cards as I was typing this. Rough estimate is that my current churning marginal earn rate is higher than my hourly rate as an anesthesiologist, as all it takes is to apply to a new card, switch it out in my wallet and repeat, it's probably 1 hour of marginal work from opening to cancelling.
I have never paid for a biz class ticket. But I've flown many legs on lay flat business class tickets. The advice I have is : ignorance is bliss.
At this point in my life, quitting churning is a luxury I cannot afford. My wife no longer wants anything less than lay-flat business if we are flying across an ocean (she's fine with upgrading to first class). I'm too filial to leave my mother in the back of the plane if she's coming along. I'm not quite at the 10MM in points but I'd say I'm at least half way there in the last 4 years. It's well worth it for me to switch a credit card every month or two.