Two thoughts:

1. What do you dislike most about flying? The answer to that may reveal a lot about whether first will be worth it to you.
2. I think you should go for it at least once without trying to do the cost benefit analysis. I suspect you will pretty quickly figure out if it is worth it to you. Maybe you will realize that you love first class and can't go back to economy. Maybe you will decide it is a total rip off. Regardless of what you ultimately decide, you will have had a new experience, you will have done something differently and tried something new. Isn't that what it is all about?

So I used to travel twice a month on Southwest, always pinching pennies, never even buying Early Bird check-in or any extras. I thought, why waste money on stuff that just enhances an experience I'm going to have anyway? Then, post pandemic, I've ditched Southwest and now fly on AA and AS, always in premium economy or first class. I also bought the lounge membership. Guess what? It's AWESOME and absolutely worth every penny. I can't explain the difference in comfort and experience between going from the Alaska N lounge in Seattle and walking on a first class flight home rather than being treated like a meat cow and crammed in the back of a crappy WN plane on an absurd connection in a godforsaken airport. I'm way less tired, less stressed, and just happier overall. Especially if you have the money and enjoy traveling, I'd spend it and never look back.

I'm perfectly content with J/C over F for international flights. I just need a safe landing, not necessarily a happy landing.

Try a good international business class (I.e., probably not a US carrier), try to get it at a low price or an upgrade at booking, and see if you feel the same way. I do. Question answered.

Yeah the lines are getting blurred on some "Business First" products... like I noted above, I'm perfectly content with a good international J/C product.

If you're in e.g. JetBlue Mint, Delta One, or an AA wide-body, the seat in domestic F is very, very much better than coach -- on par with int'l business class... which is not at all unsurprising, since in AA's case at least, many of the planes are actually repurposed from international routes during covid (not sure what will happen with those routes if/when TATL and TPAC traffic rebounds).

Most recently I paid around $750 for a Mint seat JFK-SEA. Coach would have been maybe $200 on that flight. The same Mint seat can be 2x or 3x what I paid though, depending on demand and whatever other mysterious black-box criteria airlines use to concoct their fares.

Similar to AC transcons on widebodies... the same aircraft they use for international flights with lie flat suites and the such... so much better than coach

Yes you should start flying first class. If you haven't done it, even once will be a thrill for you.

I will say this. I travel at least once a week and about 80% of the time I'm either upgraded or take advantage of a generous upfare offer so this isn't a big concern (yet) personally for me. I will say that on every flight I'm on (I fly AA) there's minimally 10 paxs, and usually more, that are so overweight there is no way they can sit in a Y seat without encouraging into a seat mate's personal space. I have a hard time believing these paxs are all being forced to buy a second seat or sitting with family members/friends that don't might them in their space. And over the past few years the number of POS seems to be exploding-no surprise given our obesity rates.

One good reason to buy F (assuming you can afford it) is that you won't have to deal with someone's body matter spilling onto you.

There are plenty of J/C products that also shields one from OPBM.

I worked for white shoe law firms and traveled in F. I was expected to work while flying, or sleep on overnight flights and go directly to depositions, meetings, etc. from the airport (and often go straight back to the airport and get on the next TATL flight home at the end of that day). That was the trade-off.

Anyhow, like you, I now fly F domestically if a flight is over 3.5 hours and I am flying by myself. My husband will fly international J (often gladly -- he is a huge fan of certain airlines' international product), but he does not like to pay for domestic F. I totally understand.

fully agreed. Also don�t forget that F includes baggage. Y usually has a separate fee for baggage. Of course tsa pre helps to negate tsa line unless pre isn�t available.
I rarely travel and when I do, no matter how short, I buy paid F. If it�s out of budget, then I won�t fly there.

This.

2-3hrs is the maximum I can bear sitting in coach, longer than that I will get J/F with miles/points or buy a reasonably priced fare. If I cannot afford it, I am staying home.

With most carriers charging $30 for the first bag and $40 for the second bag that is already good savings there, not to mention that J/F waives the $150 70lbs upcharge which has sometimes made the fare difference break more than even for me.

Something I haven't seen brought up that is important - OP, how big/tall are you? At 6'4" 215# I'm sure I appreciate FC more than some others. I often joke that my wife in (5'1" 105#) coach is how I feel in FC. If I were smaller I'd have no problem just sitting in smaller seats with less legroom but to me the extra room in more expensive seats has more value. Literally sitting with my knees buried in the seat in front of me is quite unpleasant.

This. As one who sizes in at 6'2", I've not flown too often in standard coach. Did it yesterday as a standby for LAS-LAX and, yes, my knees were in the back of the seat in front of me.

David