AOG - // You don't think that it had anything to do with Harry being a Prince of untold riches, and the chance of becoming a Duchess? //
Not for one second.
First of all, after her time in Suits, I am quite sure Ms. Markle already enjoyed a nine-figure bank balance and all the adoration and fame she could ever want or need.
Would she trade that to move several thousand miles from her family and friends, terminate her hard-won career for ever, and put herself at the mercy of the most poisonous media machine in the world with never any chance ever of having her say, and join the most famously dysfunctional family on the planet, and succumb to years of tedious protocol, interference, absence of privacy, backbiting, envy, hysterical abuse from strangers, and everything else that goes with being a Royal - unless she loved her future husband very much and was willing to do all that to be with him?
I doubt it!