The thread has lots of couples enjoying their golden years together.
So how what's the experience of somebody who is single with retirement?
To give a more realistic answer - look at something like Toastmasters.
You can be a member of one club and build public speaking & leadership skills and that's what most members do.
Then you have members that will enter the various contests to challenge themselves, thus immerse themselves further.
Many members will join the club committee/leadership group that is part of the learning.
But that just the start..
You can join a 2nd club, you can be a guest at any club in the world, you can become area, district, division leader in various roles.
You then also build up skills of a MC - that opens many opportunities.
Some people stay as a member for 2-3 years, others will stay for 20+ years. And if you like travelling, the chances are there's a club near whatever place you travel to, and you effectively find you have friends there.
To give an example - I'm currently in a officer training conference. 486 zoom attendees from Ireland and UK and got invited to make a speech in the Inverness club when I'm in Scotland in Sept. One of their members works in a distillery and he'll give me a personal tour. - Rinse and repeat all over the world