They same way they used to before Riviera, and the same way Wyndham, Bluegreen, etc. do now: by having people in the sales role who are very good at their job.
It's not as though a sharp divergence between retail and secondary markets is suddenly a new thing.
That's because until recently the sales guides could offer far more benefits from buying direct than they can now.
Buy direct and you can book at our new resorts coming online soon or in the future. Well you'd have to be living under a rock as a DVC buyer not to know that prospect is likely dead in the water for a long, long, time.
Buy direct and you'll get a nice fat discount on your Annual Pass. Dead.
Buy direct and you'll get nice merch discounts if you happen to be in the parks on the fifth Tuesday of the month between this time and this time. Disney: the masters of LOOKING like they're giving the members something when in reality they're giving almost nothing (unless you're lucky).
And the big one: buy direct and you're buying from DISNEY - the "gold standard" - you're REALLY in the club now and get the blue card. If the pandemic has done one good thing - it is my hope that this illusion has been forever shattered. Yet judging by some of the comments on this board, there appears to be more than a few cases of confirmation bias regarding direct purchase. However, on the flip side, I have read a number of threads where there is plenty of acknowledgement that direct purchase ain't what it used to be - and there's far more value in resale.
My point is: DVC buyers are not stupid. You gotta offer something to get most buyers to shell out an extra $75 a point - and they don't have a lot to offer right now over resale.
We are relatively new direct owners at RIV (we also own a resale contract from earlier). Other than being able to book at the 11 month mark for the resort we own at (which is a bit crazy calling this a benefit) - I have been mightily struggling to name one benefit received by buying direct from Disney. No annual passes for newbies - so no DVC discount on AP's. For our upcoming June trip, had to pay for individual tickets, and the 4+2 discount we did receive EVERYONE received. For the dining reservations we have booked, I've been praying there's one that ONLY offers DVC discounts (to make me feel better about my purchase) - but a quick look thru our reservations shows we'll get the same discounts with our Disney Visa. Transportation to and from airport: all resort guests get it (until none of us get it next year). Merch discounts: again our Disney Visa card appears to give the same benefit. Go to Top of the World Lounge? Nope, closed. Some special care or concern from DVC about the AP issue? Nope, pretty much got ignored and peed on.
What benefit did we get from becoming a direct DVC owner? None. We'd been better off buying a BLT resale at about $40 a point cheaper and spending the savings on a new car.
One of the reasons I hang around these boards is to keep singing this song - although there's no need for most buyers - as I said, they're not dumb (but they do have different choke points).