The amount of HP a villain has tends to vary based on what time it appears, since more players are online at some times than at others. 65m is not too unmanageable for peak times. The problem is that a lot of top players who contribute a large proportion of the damage don't bother to attack villains anymore since they don't need new items, and after a number of disappointments, most people won't spend donuts to add extra damage unless they're sure it's going down.
The amount the villain ends on is irrelevant. It would be higher, but if people see the villain isn't doing well they stop attacking it, giving a poorer impression of how much damage we are capable of doing.
The villains are designed so that we don't always win them; it's always been that way. You just have to hope we do well on another one. The devs regularly update the villains' HP in patches so I assure you they are likely keeping an eye on all the different factors and will make adjustments if we are losing (or conversely beating) too many.