My old fashioned full-sized, house-brand matress - with just a couple inches of foam and rag - is doing great after 25 years.
All of the giant stacks of foam hybrid garbage matresses are junk after a year or two.
You don't need over 3-5" of foam and rag padding, or your spring construction is no good. Polyseter fill is garbage.
And that short life is with no boingy-boingy going on.
Sadly, Simmons ain't what they used to be in the 70's.
-Ken