A decade ago during the lending crisis, the Orlando Sentinel reported that 75% of all DVC purchases were financed. This is nothing resembling "investment advice" but DVC is a rather low risk purchase since resale values keep increasing. The greatest risk comes in the first 2-3 years where the seller may not recoup what they still owe on the mortgage.
Interest adds cost to the purchase. But the question some buyers must ponder is whether it makes more sense to buy DVC + some amount of interest vs continuing to pay for cash vacations while saving to pay in full. If someone forecasts a full 10 years to pay off the mortgage, obviously there are danger signs. But in reality it's a sliding scale where every buyer must find their personal comfort level.
As someone who does work in the world of investment advice, I would never describe it as "low risk". For the vast majority of people, the amount of money "invested" in DVC is going to be a very substantial part of your overall portfolio, as most people just don't have that much in savings and investments.
There are a number of reasons why it's a very risky investment, and far riskier than other kinds of real estate. The obvious ones being:
1. You are investing in a frivolous thing. Nobody needs to go to Disney World, and nobody needs to stay at Deluxe resorts when they do go to Disney. Anything that puts a squeeze on people's ability to spend on nonessential items is bad for your investment.
2. You're investing not only in a single company, but a single part of one division of that single company. You just don't know. Maybe the entire company is on the brink of collapse and is hiding it through fraudulent accounting that the world is currently unaware of. Maybe the brand will tank itself through some scandal or maybe some investments will work out horribly. Maybe Disney keeps adding so many resorts to the DVC lineup that there isn't enough demand to meet the supply.
As far as putting your money into the hands of a single corporate entity goes, I guess Disney could be looked at as a relatively safe bet. But there is definitely a lot of risk.
And by the way, that risk works both ways. Say Disney parks continue to become more and more in-demand, and they keep adding amazing attractions that keep people hooked. And inflation drives real estate prices sky high, etc. You can be continuing to go to Disney world for cheap compared to everyone else, or you can pocket a nice return.