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maybe it's always been that way
In the olden days, the sacrifice was made in a different way. Many top riders took low paying employment with no career progression in order to make the time for high volume training.
You should still be able to compete if you are cash poor but time rich, since we have access to tools and information which were unimagined even as recently as the 1980s. Wind tunnels and Aerocoach are just short cuts used by people who are cash rich and time poor, allowing iterations of testing in one day which would takes weeks of field testing.
It does seem, that the pointy end of time trialling is very much a rich persons game. Without spending money (and thousands) on aero testing, it's very hard to be there. Strength and being generally aero just isn't enough now. Which is a shame. But maybe it's always been that way (I don't believe so).