I think it may have been Rhodes who first publicized the idea of transacting Africa although he of course was thinking stickily in terms of a railroad. I originally became enamoured of the concept while living in Lesotho in the 70s, when I first started reading all that I could find back then with somewhat limited resources.
I used to think of the various ways one could do it, passing through motorbikes (a no-go since I've never learned how to ride them), overland trucks (too painful), driving our own vehicle and abandoning at the completion (expensive), or even public transport (actually, quite feasible I thought) before stumbling onto the TDA websites and news articles. But even then, the time away from home and work, and the expense, all seemed too high a price to pay.
But time passed, and eventually, what the heck; let's try it.