It's a scam or ponzi scheme site for sure.

It's just impossible to pay 3.5% or 4.5% returns on your investment for long term. It's not at all profitable for any organization or scheme provider.

It's too high to be true.

What they do is, they will give you these high returns for first few people for some time. Until then, the first people will be getting more investors for them for getting referral bonuses. Once they have got enough investments, they will run away with all the money.