I find such sentence on the web, but is it correct?
"people should invest in the development of their city"
If that's correct, can we "invest in the development" of some specific skills? (Such as intellectual skills: you would for instance donate to a school, or some of your time)
My sentence (concerning concerning social skills) would be
"why not starting to invest in their development? "
Ordinarily a why question of this sort takes a bare infinitive as complement of the interrogative:
Why not start to invest in the development of social skills?
It is the very similar questions with what about or how about that take the gerund:
What about starting to invest in the development of social skills?
By and large the gerund occurs with why only when this contrasts with a prior gerund—in effect, as a 'mention' rather than a use of the gerund.
A: We're considering investing in the development of social skills.
B: Why 'considering'? Why not 'starting'?
