I find it to be a slightly bad choice to buy additional pension under those terms, but it depends heavily on your discount rate for the future. (Money in 14 years is worth less than money today, but by how much?)
I created a quick Sheets sheet that ignores inflation (because the pension is inflation adjusted, you can do the math entirely in "today's money"), but you still discount the future for three reasons:
1. Risk that the payer will be insolvent, may curb the payouts for some other reasons, may institute means-testing or punitive taxation of pensions for people "who don't need it", etc.
2. Risks that the buyer will die earlier than predicted.
3. Gains foregone by investing in alternative vehicles.
4. (Possibly,) you might value money at age 67 more than at age 92, in terms of being able to travel and enjoy the fruits of the money. (This is a less extreme version of 2, so I didn't count as a fourth point.)
In this analysis, assuming the inflation adjustments are "acceptable" to you, you can ignore inflation, so don't add that into the discount rate.
You are also to be able to pass on to heirs the likely surplus in any investment account, but not in a pension.
For these reasons, I chose a discount rate of 3%, which makes it a breakeven proposition at age 93.
https://docs.google.com/spreadsheets/d/1lSm3MtbNyQd1spGi7dKrtsEK6rIYcdXmelxTEbJXHsc/edit?usp=sharingTo the extent that you consider buying in under these terms, I think you're giving up a sum of money overall, but may be buying "ease" or piece of mind, so think of this as an insurance purchase of sorts. It's not wrong to buy insurance, but it does cost you money overall and one should probably not buy excessive amounts of it.