It's true - whining is not particularly effective, as a personal response to increased anxiety.
And, there's other contexts to factor in - what we've done and are doing to ourselves that contributes to increased anxiety (and more serious mental pathologies) quite beyond what an individual can conquer with a good old fashioned British stiff upper lip, or American gung-ho can-do, or Finnish sisu, or whatever. It's quite tangible, even the virtual aspects, and researched. It affects the youngers more because they've been exposed to more of it more often and/or higher quantity in more places than olders. Exposed from an age where impacts are greater, namely birth or before, in the case of 20-somethings on down.
A partial and un-elaborated list includes, but is not limited to: chronic over-stimulation on all fronts; lack of quiet; lack of dark; lack of peace (personal to global); increasing corruption and degradation of civic/public institutions and/or personalities and/or beliefs; multiple forms of contamination/corruption of all life essentials (air, water, food, light, shelter, information, human relationships, etc.); psychologically harsh built environments; pervasive psychological manipulation without consent. For starters.
So no surprise more and more people, especially youngers, are experiencing more and more anxiety. What triggers it versus what they attribute it to may be way off the mark. But it's not going to be fixed by individual effort of will or "stop whinging" lapel buttons alone. It's a massively implicated systemic pathology, and "anxiety" as described here is the least of it.