Normal bumps in the market won't impact DVC prices, IMO. My sense is that the majority of DVC owners aren't selling bits of their portfolio to buy points, I know I didn't. I do think once interest rates start to return to historic norms we will see significant changes in real estate values - including DVC which is frequently financed, unless there's also meaningful increases in wages.
I don't see DVC as an investment - it's more like a car, I paid a lot to buy the thing, I have to pay for gas to keep the car running just like I pay MFs to use my points, I have to pay for tune ups and repairs just like I pay for tickets and airfare to use my points. When I'm done with my car maybe I'll get some residual cash back, when I'm done with my DVC maybe I'll get some residual cash back (unless I hold to the end.) My investments in the market I don't have to pay anything for once I'm invested, the dividends I can spend or reinvest, if I choose wisely I should see 6-8% per year growth long term and when I liquidate I'll see my initial investment plus my gains.