Anecdotally, it's mostly boomers, but there's a handful of 20's-30's too. I went on my first and only cruise, a Carnival, with five friends circa 2016. We split two rooms and a drink package. The casinos were packed with the eldest, and the younger folks just double-fisted mixed drinks all day (our plan). Saw at least a few get carted off the pool deck in wheelchairs. The food was legitimately great, never seen such excess before or since. Everything else was meh, including the stops in the Bahamas (though that was mostly due to the weather being terrible).

4/10 experience at best and the value we managed to get probably hasn't existed for years now.

The staff were innumerable and worked so hard to facilitate a good experience for all the passengers. Not surprising to hear they're underpaid. :/ One more reason I've not sought out another cruise experience.