These cryptocurrencies are neither U.S. dollars nor Singapore dollars.
This cryptocurrency is designed to remain pegged to the U.S. dollar. Whether it actually will stay pegged to the U.S. dollar or not is a very separate question.
Your monthly Singapore dollar pay is presumably exceeding regular basic household expenses, which would mean you have Singapore dollar emergency reserve funds in excess of 6 months. That seems perfectly fine, or better than fine. Unless you're expecting some "lumpy" Singapore dollar expense in the not too distant future, for example a wedding in Singapore 2 years from now.
I think you have two basic portfolio allocation problems: all of your savings (except for emergency reserve funds) are in cryptocurrencies, and then you have 80% of those savings pegged specifically to U.S. dollars. So you lack both asset class and currency diversity. Unless you're fairly close to retirement in the United States, or in a country that uses the U.S. dollar or has a currency pegged to the U.S. dollar, you are indeed over-allocated to U.S. dollar proxies. But you can solve both problems at once by investing in a low cost global stock index fund, as a notable example.
You're in a very different situation. VWRA and CSPX are stock funds, not currencies or currency proxies. You don't even need to consider hedging a currency position when you're not holding a currency position.
As a separate matter, I don't think it makes sense to overweight any particular country's stock market(s) with the possible exception of modest overweighting when you plan to retire in that country (when overweighting might make some sense, although only a little). Presumably you're not planning to retire in the United States, and don't have the ability to do so in immigration terms. Hence I don't think you ought to invest in CSPX.
