This thread is largely about college educated folks who represent a small minority of diversity lottery applicants. As to why the DV lottery has grown, I suspect it has a lot to do with it just having become more visible and known, growing hand in hand with increased access to internet and ability to apply.

Sure, if we are talking about the top end we can check the O-visas, the "extraordinary ability in the sciences, arts, education, business, or athletics" ones, both the applications and the issuance of those went up even more than the DV applications:

https://en.wikipedia.org/wiki/O_visa#Number_of_visas_issued_...