For most making a 40-50 year commitment to The Walt Disney Company is not a risk taken lightly. While the potential impact on one's finances is obvious, there is also a great degree of uncertainty over what the next several decades may hold.
Material changes to either the Disney Vacation Club program or the Disney parks & resorts would have an immediate impact on members. The changes could be somewhat minor (and subjective) such as a declining quality of service at the parks & resorts or DVC policy changes. Or we could witness major upheaval like the sale of one of Disney's key business units (hotel operations, theme park operations, dining, DVC.)