I think the headline is an exaggeration. Though I don’t see why Sarkozy would want to downsize. According to Wiki, there are @ “7,700 men in eleven regiments and one sub-unit”.
Not very many.
You were ahead of me in the calculation: the 1b Euro figure works out to about 129K per man so it must include health care, family support and perhaps even pension costs. This is not surprising when you look at the US defense budget the bulk of the costs remain in personnel; these costs are tricky to calculate.