I am NOT a financial consultant, but according to Wikipedia:
INVESTMENT - To invest is to allocate money in the expectation of some benefit/return in the future. In other words, to invest means owning an asset or an item with the goal of generating income from the investment or the appreciation of your investment which is an increase in the value of the asset over a period of time. When you invest it always requires a sacrifice of some present asset that you own today such as time, money, or effort.
Thus, for some people DVC is a true investment, but obviously it is just a timeshare
It's largely semantics, but I would dispute it is really ever an investment.
When investing, the central and main purpose is the expectation of financial growth and return in the future.
Though many people have managed to make a "profit" over the course of their DVC ownership, the main purpose of virtually every buyer is to USE the purchase, to stay in the resorts. Even those who have managed to make a profit, the annualized return is quite small.
So I suppose there are a few buyers out there who bought DVC, never really plans to use it, they keep paying the dues, maybe they rent it out every year, and they plan to eventually sell it for a profit. But such "investment" strategy would basically under-perform most traditional investments, with greater risks than most other investments.