In this case, i was wondering how does Etiqa (Dash) and SingLife maintain its guaranteed (relatively higher) interest rate?

I believe the factors below play a role:
1) Company strategy to get customer exposed to their products. That's why there is always a cap (10k/20k). Anything more, the interest is much lower.
2) Underlying investment can be a longer investment timeframe for company. Like if 5000 people deposit into their account, they can use 50% for riskier investment and remaining for less risky product as it is unlikely everyone withdraw at once. It is proven over time, market is always going up.

The company walking on a delicate line between risk/reward.