This is from a while back:
https://poetsandquants.com/2012/01/17/the-ultimate-ranking-school-rejection-rates/If the article is to be believed in then we should assume INSEAD has a lower yield (higher reject rate) than top tier US schools. (Read 2nd last paragraph first page).
Suppose that INSEAD (similarly ranked to CBS on FT) has a yield of 80% (probably lower), this means that up to 100 offers will be turned down. To cater for this, the waitlist must be massive if they had to match you off on all aspects of the candidate that rejected the offer.
What does this mean? Absolutely nothing...
If you are banking on INSEAD and you are on the waitlist right now, then good luck, you'll need it! If you are more realistic about it you would have probably applied (or is applying) to other schools so most likely you will be doing MBA somewhere next year anyway. ("If you can't be with the one you love, love the one you're with") In fact the way I see it, think of being on the waitlist as being dinged. If they call you, then Christmas has come early, if not, well there wasn't much expectation to begin with anyway....