The 1% are not equally distributed, or indeed necessarily distributed at all, in all the places with excessive pension obligations. Taxing them is not a general solution.

The other problem is that we don't just need to come up with money; we need to find ways to convince/force governments to stop making these promises in the first place. A government promise about something it'll do 30 or 40 years in the future is not quite worthless, but it's just not an institution capable of reliably keeping it.

(Whatever politics you think drives me to say that, I mean that and I mean lots of other things too. If nothing else, in the general case, a legislative body can not truly constrain future legislatures, who can always just vote to not keep their old promises, made by people who are mostly not here anymore, for constituencies that were growing in power 30-40 years ago but are now dying off and not very useful to the current 30-40-year-olds in the legislature. Looking to governments to keep promises so many decades in advance is far more risky that many people seem to account for on all kinds of levels. The history of the 20th century suggests that counting on your government to even exist in 40 years is, in general, not the safest bet!)