Many consumer items become outdated and superceded over time, like the phone I am typing this on, or VIPs as you mention.
Early adopters usually pay a premium to get an item earlier, before it becomes more affordable and mainstream. This gives a period of exclusivity and an extended window of usefulness before the item becomes outdated.
When monsters first hit the war shop they are very expensive. That makes sense: players who buy at that higher premium pay for the privilege of playing with the monster while it is still rare and exclusive.
I spent a lot of war coins for the privilege to rank Nishant's Bodyguard, and was happy to do so because of the team evasion mechanic... but it didn't work!
Now it works, and players can rank her up for less than half of what I paid. I got nothing for the early adopter fee I paid.