I guess it depends on how the actuaries structure the product. We do have capital guaranteed plans too, such as pruwealth, but they are plans without a cashback. Meaning you have no option to withdraw part of your money over the years and will only get the money at the end.
But still, if really, one wants that cashback so much, I rather you put your money into the bank savings account. Why pay for a savings plan that has cashback but with distribution costs etc. these unnecessary costs that can be avoided. Or is it because you want more % returns? If so, park your money inside STI ETF.
From my understanding in this PruFlexiCash, even if you never cashback for the next 24 years, your guaranteed is still lower than total premiums paid. This "guaranteed sum" is simply equivalent to your yearly cashback.
Using the bank deposit example. I put in $1 per year, 2nd year onwards I can take out $0.40, if I never take out I should have $25 but the bank can only give me $10 as guaranteed, despite I did not take out any money.
So ultimately, not only it depends on how the actuaries structure the product, it depends on how the agent presents the product. You cannot deny there are people out there who smoke their way through to misled clients. I was a victim to such rubbish many years ago and today, there are 4 insurance companies with I am severely dislike, or I would suggest, to the point of hatred.
Anyway to the TS, my immediate suggestion without knowing you and your financial liabilities is to hold on to the plan and accumulate the cashback. When you know another good place to park your money or if you need the money for an emergency, you can make use of the accumulated cashback.
Once activated, your maturity value will drop. Thats why, never activate it and keep it accumulated.
But if that is the case, park your money inside bank account is logical.