Most of my campaigns reach a planned or natural climax point. They often tootle on a bit after that then fade out. Trying to recall specific significant campaigns:
'80s & '90s:
1. AD&D age 12-13, I don't recall a climax ending. Actually, there was barely a consistent world, either. But plenty of fun. We played Fighting Fantasy, too.
2. Paranoia age ca 14-15, don't recall any climax, just lots of fun.

3. AD&D age ca 14-18 & subsequent to ca 22, but the main campaign ended when the PCs defeated Graz'zt's champions and saved the world.
4. & 5. AD&D ca 16-21, two single player AD&D campaigns where the PC reached demigod & then quasi-deity level before getting killed.
All of those but the Paranoia 1 were same-universe & same rules stuff though, they could be seen as a single mega-campaign. Things back in the days of childhood were a lot less compartmentalised.
Post 2000:
6. 3e Gaxmoor campaign(s), climax at ca 17th level when PCs turned back the Mongali Horde.
7. 3e Lost City of Barakus, climax at 7th/8th level when PCs killed Devron the Lich.
8. 3e Willow Vale campaign, climax at 6th-8th when PCs destroyed the Master of the Desert Nomads.
9. 4e Vault of Larin Karr game, again ending ca 8th level, the Battle of Pembrose was sort of a climax, but game ended in bathos when 2 PCs got burnt up by some hell hounds & the 3rd ran away.
10. 1e AD&D City State online game was a picaresque, no real climax.
That must be leaving out tons of campaigns though, like
Sector Antaris, a Traveller PBEM I ran in the late '90s, or the
Ea: Time of Chaos pbem.