Wonderful presentation! Thank you! But, my two cents' worth is that while ability doesn't have that much to do with success, it is very closely linked to success in one fundamental manner. And, that manner is that each successful person always possesses the ability to be persistent, perseverant, and disciplined!
So, yes, in this way, ability plays a critical role in each individual's success - but like all things associated with true success, it is never overtly visible!
Once again, thank you for the presentation!