"Contemptuous" is a bit strong, particularly if the OP has to travel before or after that weekend anyway. Being more willing than most to take the benefits of VDBs is not wrong.

Morality has absolutely nothing to do with the number of people who show up for their scheduled flights. United allows overbooking to the point where the revenue from overbooked flights is greater than the cost of VDBs and IDBs. Overbooking allows them to fill their planes more profitably. If they feel that rapacious VDB seekers are taking advantage of this practice, they can adjust number of fares they sell.

If you want to talk about right and wrong, why not discuss those instances when involuntary denied boardings prevent people from getting on the flights they paid for? Is the airline wrong in such cases? Isn't the person who's willing to take a bump saving another passenger a lot of inconvenience? There are a lot more sides to this issue than whether a VDB seeker is "contemptuous" for selecting oversold flights.