I am sorry you are in this situation. Like many others, I had optimistically booked a number of activities during the Christmas period that I am now not able to attend due to changes in the travel restrictions. Some are refundable, some are not. It's a miserable situation all round.
FWIW: Switzerland was one of the few places that kept it's ski resorts open last year. They did bring in a quarantine for travellers from the UK recently but that was lifted and they have also lifted the day 4-7 test requirement. Switzerland would be a possibility but I guess not if the rest of the group will be in France.
There have been a few things over the last two years where I have had to mentally write off the cost of the flight and figure that I was saving the amount of money I would have spent while on the trip and just write it off to just one more thing that COVID has brought.
Yes, you could have bought fully flexible and fully refundable tickets and if you look back over all of the flights that you could have done that for in the past 10 years, it would have cost you significantly more that the lost cost of this individual flight.
I think you need to accept it, feel a bit grumpy about it and have a small treat with the money you have saved by not having to test, pay for ski passes, transfers, expensive overpriced food etc etc.