Rail pass vs Point to Point - Am I missing something?

You are probably comparing a high speed train ticket purchased, day of travel, to the Eurail pass. High speed train tickets can be purchased in advance (about 3 months), typically for half the price. Also, I've never used a rail pass, but I believe you would have to pay for a seat reservation.

I used a German Rail pass in 1988 (16 days, every day, for $160 - $10 a day). I think that, even at the lower ticket prices in 1988, I still made it pay.

I again used a rail pass (again a German Rail pass) in 2000. When I got back from the trip, I added up the point-point price of all of the rail connection I had made and figured I had just about broken even. And that was before such saving as Länder- and Sparpreis-Tickets.

Now, before every trip, when I have a good idea of what connections I will be taking, I compare the price with discounted tickets and passes, and a rail pass never comes close to being competitive. My style of travel is probably different from yours; if you do a lot of jumping about, long distances every day, you might save money with a rail pass. But you should do the comparison, you probably won't save with a rail pass.

I think the main point is, for France, Nice to Paris, that is a high speed train. Yes you can get a one day Eurail pass for 75 euro, and a month out a ticket is 1.5 to 2 times that, BUT...then you need to pay and secure a reservation for when you want to travel at an additional cost, plus the time and day you want to travel may not be available for a Eurail pass holder. You also can not get a reservation without a pass, and to buy a pass is likely mostly non-refundable.

If you are super flexible, you might make everything work, if you need to travel the morning of X date, it might not happen.

if that sounds right or I might be missing something

There are a limited number of seats available to Eurailpass holders on the TGV. You also have to pay a compulsory seat reservation fee (10 to 20 EUR for domestic trains) to get one of those places. Read this FAQ about Eurail constraints:
https://www.eurail.com/en/plan-your-trip/about-reservations/reservations-france

If you buy point-to-point tickets in advance you will usually save money. Make sure you are looking at prices on the SNCF website for the day you plan to travel. For example:
1) Nice to Paris tomorrow (July 20) - prices range from 99 to 142 EUR and several of the trains are fully booked.
2) Nice to Paris in 2 months (on Sept 20) prices currently range from 29 to 72 EUR.

In Europe the way to save big on high-speed train tickets is to buy them when they first go up for sale. SNCF— France’s national train company -—has discounted “Prem’s” tickets for TGV trains that first go up for sale online
3 months in advance of the train’s departure date. You didn’t say what date you were planning to travel from Nice to Paris. A quick check of high-speed trains traveling two months from now on September 19 shows there are still tickets for as little as $35. In October there are $29 TGV tickets available. You can quickly check what trains schedules and ticket prices look like for the date you want at www.TheTrainline.com.

www.SNCF-connect.com is the website to get them without any booking fees.

Another thing to consider, is that on SNCF, a rail pass only gets you from point A to point B by the lowest level train available. anything above a regional milk run, definitely a TGV, probably requires a "passholder reservation". This is more than a simple seat reservation. It is a surcharge for using a train that SNCF considers better than the lowest level provided by the rail pass. These pass holder reservations are not cheap, particularly for a TGV, and the number per train is limited. You might find that you cannot get on a specific train with your pass even though it is not sold out and there are full fare seats available.

Thank you to everyone for your replies, they were all very helpful. It looks like there are many ways to do this, but the bottom line is that I waited too long to get the low-priced tickets (it's a month and a few days out). Fortunately, I was able to get seat reservations on the TGV using a Eurail pass. Cost was 24 Euro (additional to the Eurail pass).