Most if not all want to become old, but few if any want to be old.
Its literary effect trades on equivocation.
In one sense, an old thing is a thing that has been in existence a long time. Now something can be in existence a long time without getting old in the second sense. Consider a Roman coin in pristine condition, preserved out of circulation by numismatists over the centuries. Very old, but not worn out.
Something analogous is true of humans. There are 90-year-olds who are hale and hearty and compete creditably in foot races. And there are 40-year-olds whose bodies are shot.
A man who gets old calendrically cannot help but age physiologically. But the rates of physiological ageing are different for different people.
It is conceivable that one get old without getting old. It is even conceivable that one get old while getting younger. Those are paradoxical sentences that express the following non-paradoxical propositions: It is conceivable that one get old calendrically without getting old physiologically. It is conceivable that one get old calendrically whle getting younger physiologically. The conceivability and indeed imaginability of the latter is the theme of the Twilight Zone episode, A Short Drink from a Certain Fountain. I should adde for the aficionados of modality that conceivability does not entail possibility.
The expression is paradoxical, but the thought is non-contradictory. The thought, expressed non-paradoxically is: Most if not all want to live a long time, but few if any want to suffer the decrepitude attendant upon living a long time.
One logic lesson to be drawn is that a paradox is not the same as a contradiction.
It is therefore a mistake to refer to Russell's Antinomy as 'Russell's Paradox.'