First, you can decide to buy (or not to buy) VIP any day of PoV. If you are not convinced if you can reach descent rewards, you can wait till you have it clear.
Second, dividing PoV into “beginner”/“advanced” mode has issue. You need to choose the mode at the beginning not really knowing if you complete it easily or miss the best reward because of something. For example you can have (for some unexpected reasons) less or more time for playing a game and this may affect your PoV. And then you pay for your choice - you cannot alter it. Here is also a very difficult problem (unsolvable I think): how to make rewards of “advanced” mode to be worth of additional effort (and risk of not completing it) keeping it only “little” better than those of “beginner” mode. This is not the case of the current design - you can try to reach as far as possible.
Third, most of challenges, require only regular play (well, titan challenge require being in an sufficiently active alliance that kills 6* titans). It is achievable even by beginners. The only challenge that cannot be completed by beginners is “complete challenge event” challenge. But it is already discussed here: Refine "Complete a Challenge Event" Valor Challenge to Provide Flexibility in Completing Path of Valor
There are also some daily quests that can be difficult to complete by beginners: finishing some stages of season 2 maps. But players that can complete the final stage of rare quests probably can complete also this daily quests. There were also the daily quests of crafting Super Manna Potion, but they have been apparently withdrawn from PoV.
I think, that the solution of dividing PoV into different modes you choose at the beginning would produce more problems than it solves.